A pure substance will preferably emerge as a network of large crystals after recrystallization. If not this then, it may be appropriate to reheat the flask and allow the contents to cool more slowly. Thus, a is the correct option.
The procedure used to purify an impure compound in a solvent is called recrystallization. The concept used here is that the solubility of most solids increases with an increase in temperature.
Recrystallization is also known as a method of fractional crystallization. Following recrystallization, a pure substance will preferably seem like a network of large crystals. It may be useful to reheat the flask and allow the contents to cool further slowly if this is not the case.
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In the following acid-base reaction,
HPO42- is the
H2PO4- (aq) + NH3(aq) → HPO42- (aq) + NH4+(aq)
А
B
С
acid
conjugate
acid
conjugate
base
According to the Brnsted-Lowry acid-base theory, HPO4 is the conjugate base of H2PO4 and is thus.
A reaction in chemistry is what?When atoms' ionic bonds are generated or ruptured, chemical events take place. The chemicals that initiate a chemical change are known as reaction mixture, while the regard to the structure as a result of the reaction as known as products.
What does a reaction simply mean?An action made in response to anything is called a reaction. Your parents' reaction when you tell them you want to move out will show you how upset they are about it. The nature of a reaction is frequently physical. The behavior of a chemical when mixed with another material is referred to as a chemical reaction.
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why is iodide a stronger reducing agent than bromide
Iodine is not as effective an oxidizer as bromine. In order to produce iodine, bromine can strip iodide ions of their electrons, and the iodine cannot recover its electrons from the resulting bromide ions.
Sulfuric acid concentration working as an oxidizing agent
containing chloride or fluorine
The oxidizing power of concentrated sulfuric acid is insufficient to oxidize fluorine or chloride. Only the steamy vapors of the hydrogen halide—hydrogen fluoride or hydrogen chloride—are generated in those circumstances. Fluoride and chloride are not powerful enough reducing agents to decrease sulfuric acid in terms of the halide ions. For iodides and bromides, this is not the situation.
with bromine
Sulfuric acid can be reduced by bromide because it is a powerful reducing substance. In the procedure, bromine is produced from bromide.
The oxidation state of sulfur changes from +6 to +4 when bromide converts sulfuric acid to sulfur dioxide gas.
In actuality, the steamy hydrogen bromide fumes tainted with brown bromine vapor serve as evidence of this interaction. Since sulfur dioxide is an invisible vapor, it is impossible to see it.
Using iodide
Iodide is a more potent reduction agent than bromide, and sulfuric acid converts it to iodine.
Sulfuric acid reduction is trickier than bromine reduction. It can be lowered in three stages using iodide.
(Sulfur oxidation state = +4) sulfuric acid to sulfur dioxide
pure sulfur to sulfur dioxide (oxidation state = 0)
hydrogen sulfide from sulfur (sulfur oxidation state = -2).
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For each of the following key terms, match the correct definition. saturation temperature of saturation evaporation change of state from a liquid to a gas dew point change of state from a gas to a liquid relative humidity ratio of vapor pressure relative to vapor capacity condensation water vapor pressure equal to vapor capacity latent heat energy stored or released during a phase change
Answer:
saturation: a state in which a solution or a vapor is holding the maximum amount of solute or vapor that it can hold under the given conditions of temperature and pressure
temperature of saturation: the temperature at which a solution or a vapor becomes saturated at a given pressure
evaporation: the process by which a liquid changes to a gas or vapor below its boiling point
dew point: the temperature at which air becomes saturated with water vapor and dew or frost begins to form
relative humidity: the amount of water vapor in the air relative to the maximum amount the air could hold at a given temperature, expressed as a percentage
vapor pressure: the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature
vapor capacity: the maximum amount of water vapor that can be held by the air at a given temperature and pressure
condensation: the process by which a gas or vapor changes to a liquid or solid
latent heat: the energy absorbed or released by a substance during a change of state (e.g., melting, boiling, condensing) that does not result in a temperature change
ratio of vapor pressure to vapor capacity: relative humidity
3. If possible and with your teacher's approval, carry out your investigation. Make a data table and record your observations there. Make a note of any unusual or missing data that might be caused by experimental error.
The activity described is an investigation, which is a scientific process of collecting data through observations, experiments, and analysis to answer a specific question or to solve a problem.
How can the activity be executed?To execute this activity, you need to obtain the necessary materials and equipment, and conduct the experiment as per the guidelines provided.
You should record all your observations, measurements, and data in a table, noting any unusual or missing data that may be due to experimental error.
It is important to obtain your teacher's approval before conducting the investigation to ensure that you are following proper scientific protocols and safety guidelines. Finally, you will analyze the data collected to draw conclusions and communicate your findings.
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Heat of combustion chemistry
The heat of combustion per gram of candle for each trial is:
Trial 1: Heat of combustion per gram = 30.8 kJ/gTrial 2: Heat of combustion per gram = 30.8 kJ/gTrial 3: Heat of combustion per gram = 26.4 kJ/gWhat is the heat of combustion per gram of candle for the trials?To calculate the heat of combustion per gram of candle for each trial, we use the formula below:
Heat absorbed, Q = mcΔT
where;
m is the mass of waterc is the specific heat capacity of water (4.184 J/g·°C)ΔT is the temperature changeSince the density of water is 1 g/mL, the volume of water = mass of water
Trial 1:
mass of candle burnt = 0.12 g
temperature change of water = 8.1° C
volume of water = 99.9 mL
Q = 99.9 * 4.184 * 8.1
Q = 3390 J or 3.39 kJ
The heat of combustion per gram = 3.39/0.12
The heat of combustion per gram = 28.3 kJ/g
Trial 2:
mass of candle burnt = 0.11 g
temperature change of water = 8.1° C
volume of water = 100 mL
Q = 100 * 4.184 * 8.1
Q = 3390 J or 3.39 kJ
The heat of combustion per gram = 3.39/0.11
The heat of combustion per gram = 30.8 kJ/g
Trial 3:
mass of candle burnt = 0.13 g
temperature change of water = 8.2° C
volume of water = 100.1 mL
Q = 100.1 * 4.184 * 8.2
Q = 3430 J or 3.43 kJ
The heat of combustion per gram = 3.43/0.11
The heat of combustion per gram = 26.4 kJ/g
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A chef finds a sealed container consisting of an ingredient that goes into his restaurant’s secret sauce. The ingredient’s molecules are moving in place. What will happen if the chef causes the ingredient to change phase by transferring energy into it?
After the phase change, the ingredient’s molecules will move . . .
answer choicesa. faster, and the ingredient will be a solid.
b. faster, and the ingredient will be a liquid.
c. slower, and the ingredient will be a solid.
d. slower, and the ingredient will be a liquid.
b. faster, and the ingredient will be a liquid.
Suggest a method for separating the peptides produced by chymotrypsin treatment.
Check all that apply.
1) Electrophoresis
2) Chromatography on a cationic column, at pH=7
3) Size exclusion chromatography
4) Chromatography on a anionic column, at pH=4
The method for separating the peptides produced by chymotrypsin treatment are Electrophoresis, Size exclusion chromatography. The correct option are 1) and 3).
The Electrophoresis will be used to separate the peptides based on the charge properties and the size. The Peptides with the net positive charge would be move towards the negative electrode, and while the peptides with the net negative charge would be move towards the positive electrode.
The Size exclusion chromatography can be used to separate the peptides on the basis of the size. The Peptides that are the larger would be elute the earlier, while the smaller peptides would be elute the later, as they will pass through the porous stationary phase. Therefore , the correct options are 1) and 3)
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Which equation is correct?
A. TC + or - WCA = TH.
B. TH + or - DEV = MH.
C. MH + or - VAR = CH.
The equation that is correct is TC + or - WCA = TH. The correct option is
A.
The given equations are related to the magnetic compass errors.
The full form for the above equation is as follows :
T is the concerning TRUE North it is use to plotter and the latitude
M is Regarding the MAGNETIC North that is the True North +/- Deviation.
C is to the COMPASS North that is the Magnetic North +/- Compass card deviation in the system
C is Plotted COURSE in the map that is no wind correction is applied.
The order is as :
TC = True course
VAR = Variation
MC = Magnetic course
WCA = Wind correction angle
MH = Magnetic heading
DEV = Deviation
CH = Compass heading
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what dangerous gas is produced by the decay of radium-226?
Answer:
Radium-226 decays by alpha particle radiation to an inert gas, radon-222, which also decays by alpha particle radiation.
Explanation:
dissolving a solute such as KOH in a solvent such as water results in A.) a decrease in the vapor pressure of the liquid B.) a decrease in the boiling point of the liquid C.) no change in the boiling point of the liquid D.) an increase in the melting point of the liquid
Dissolving a solute such as KOH in a solvent such as water results in a decrease in the vapor pressure of the liquid.
This is because the solute particles occupy some of the solvent space and reduce the number of solvent molecules at the surface of the liquid, which decreases the rate of evaporation and hence the vapor pressure.
The presence of a non-volatile solute also affects the boiling point of the liquid. It causes the boiling point of the solution to be higher than the boiling point of the pure solvent, a phenomenon known as boiling point elevation.
This happens because the solute particles attract solvent molecules and reduce the ability of the solvent molecules to escape from the liquid phase as vapor, which requires an increase in temperature to boil the solution. Therefore, option B ("a decrease in the boiling point of the liquid") is incorrect.
The solute-solvent interaction also affects the melting point of the solvent. In general, the presence of a solute lowers the melting point of the solvent due to the disruption of the solvent-solvent interactions by the solute-solvent interactions. Therefore, option D ("an increase in the melting point of the liquid") is also incorrect.
Option C ("no change in the boiling point of the liquid") is not correct either, as the boiling point of the liquid is affected by the presence of the solute in the solvent, as mentioned earlier.
Hence, the correct answer is option A ("a decrease in the vapor pressure of the liquid").
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Marsupials are a group of mammals that give birth to very immature young and raise them in a pouch. Opossums, kangaroos, and Tasmanian devils are all marsupials. Marsupials are common in Australia and South America. Previously scientists thought marsupials originated in Australia, but new evidence confirmed that all marsupials evolved from a common ancestor in South America. What is the most likely explanation for why marsupials are related in Australia and South America? Group of answer choices A huge asteroid struck Earth and the impact broke the two continents apart. An ice age froze the ocean surface and marsupials migrated to Australia. The continents were once joined into a supercontinent that slowly broke apart. A series of earthquakes and volcanoes separated the two continents.
About 100 million years ago, in South America, marsupials first appeared. Australia, Antarctica, and South America were all connected at the time to form one large continent. Australia and Antarctica gradually separated from South America and developed into independent continents.
Why is marsupials more in Australia than South America ?
The diversity of marsupials is thought to be higher in Australia than in South America because there were no terrestrial placental mammals there in prehistoric Australia to compete with marsupials. The only other large mammal that uses hopping as its main mode of propulsion is the kangaroo.
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in which type of extracellular fluid can an animal cell undergo lysis?
Explanation:
An animal cell can undergo lysis in a hypertonic solution.
Indigestion tablets neutralise stomach acid.
What does this tell you about indigestion tablets?
Answer: It is a alkaline substance/base and it is an antacid
Explanation: Neutralisation is the reaction between an acid and a base, in this scenario, it is the stomach acid and the indigestion tablets (base). They react to form salt and water
Mass (g) to mass (g)
2Na + 2H2O >2NaOH+ H2
How many moles of NaOH are produced if 120 grams of H2O are available?
Answer:
4.44 g
Explanation:
First, we need to determine the limiting reactant. The balanced chemical equation is:
2Na + 2H2O → 2NaOH + H2
From the equation, we see that 2 moles of sodium reacts with 2 moles of water to produce 1 mole of hydrogen.
Moles of Na in 120 g of Na:
Molar mass of Na = 22.99 g/mol
Number of moles of Na = mass/molar mass = 120 g / 22.99 g/mol = 5.22 mol
Moles of water in 80 g of H2O:
Molar mass of H2O = 18.02 g/mol
Number of moles of H2O = mass/molar mass = 80 g / 18.02 g/mol = 4.44 mol
Since 5.22 moles of Na requires 5.22 moles of H2O, water is the limiting reactant.
The moles of hydrogen produced is equal to the moles of the limiting reactant, which is 4.44 mol.
The mass of hydrogen produced is:
Mass = number of moles x molar mass
Mass = 4.44 mol x 1 g/mol = 4.44 g
So the grams of hydrogen produced by the 120 grams Na and 80 grams of water is 4.44 grams.
The first law of thermodynamics states that the total energy in the universe is:a. decreasingb. increasingc. constantd. being converted to free energye. being converted to matter
The first law of thermodynamics states that the total energy in the universe is constant. This means that the total amount of energy in the universe is always the same, and it cannot be created or destroyed.
Energy can be converted from one form to another and transferred between objects, but the total amount of energy remains the same. For example, if two objects are interacting and one object gains energy, the other object must lose the same amount of energy. This is because energy can be neither created nor destroyed, and so the sum of the energy from both objects must remain the same. Mathematically, this can be expressed as: Energy before interaction = Energy after interaction. This law is often used in calculations to determine the amount of energy that an object has gained or lost in a given situation. The equation for calculating the change in energy (ΔE) is: ΔE = Efinal - Einitial
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to find the order of a reaction with respect to one reactant, you will monitor the
Answer:
hydrogen + oxygen is equal to water Potassium Chloride + oxygen there are reaction
a scientist mixes 0.02 g of a strong base in 83 ml of water and obtains a ph of 12. he then realizes that he forgot to label the container and forgot what base he added. what is the most likely the identity of this base?
a. LiOH
b. NaOH
c. RbOH
d. KOH
The calculated pKb value of 4.22 is closest to the pKb value of LiOH, so it is likely that the strong base added to the solution is LiOH. The most likely identity of the base added to the solution is LiOH.
To determine the identity of the strong base added to the solution, we can use the pH value and the amount of the base added.
First, we need to calculate the concentration of the strong base in the solution. We can do this by converting the mass of the base (0.02 g) to moles, and then dividing by volume of the solution (83 mL or 0.083 L):
moles of base = (0.02 g) / (molar mass of base)
molar mass of NaOH = 22.99 + 16.00 + 1.01 = 40.00 g/mol
moles of NaOH = (0.02 g) / (40.00 g/mol) = 0.0005 mol
concentration of base = moles of base / volume of solution
concentration of base = 0.0005 mol / 0.083 L = 0.006 M
Next, we can use the fact that pH = 14 - pOH to calculate the pOH of the solution:
pH = 12
pOH = 14 - pH = 14 - 12 = 2
Now we can use the pOH and concentration of the base to calculate the pKb of the base:
pKb = pOH + log([H₂O]/[base])
pKb = 2 + log(1/[0.006])
pKb = 2 + 2.22 = 4.22
Finally, we can compare the pKb value of the base to the pKb values of known strong bases to determine the most likely identity of the base. The pKb values of some common strong bases are:
LiOH: pKb = 0.19
NaOH: pKb = 0.20
KOH: pKb = 0.17
CsOH: pKb = 0.08
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what is definition of catalyst ?
In chemistry, a catalyst is any substance that accelerates a reaction without being consumed. Enzymes are contains natural catalysts that are responsible for many important biochemical reactions.
Just about all solid catalysts are steels or their oxides, sulfides, and halides, as well as the semimetallic components boron, aluminum, and silicon. Gaseous and liquid catalysts were also commonly for use in their pure or in conjunction with suitable carriers but rather solvents.
Solid catalysts are widely diffused in other substances known as photocatalysts. In general, a toxic effect is a reaction between a catalyst and a reactant that produces chemical intermediates capable of reacting more readily between themselves or with another reactant to produce the desired end product.
The precursor is regenerated during the reactions between the precursors and the reactants. The modes of reaction between catalysts and the heterogeneous catalysts vary greatly and are frequently complex in solid catalysts.
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What is NO compound called?
NO is called nitric oxide.
NO is a chemical compound composed of one nitrogen atom and one oxygen atom. It is a colorless gas that is a free radical, meaning it has an unpaired electron. Nitric oxide is an important signaling molecule in many physiological and pathological processes in the human body.
It plays a crucial role in the regulation of blood pressure, immune system function, and neurotransmission. Nitric oxide is also involved in the formation of smog and acid rain in the atmosphere, as well as in the production of fertilizers and explosives in industry.
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Explain the octet rule. Why are hydrogen and helium exceptions to the octet rule?
Discuss electron configurations in your answer.
Hydrogen and helium have only one electron shell. The first shell has only one s orbital and no p orbital.Therefore, it has only two electrons. So, these elements are most stable when they have two electrons.
What do you mean by the term octet rule ?The octet rule states that an atom loses or gains an electron in order to achieve a stable electronic configuration. It defines the tendency of an atom to have eight electrons in the outermost shell.
Both helium and hydrogen are stable with two electrons in the valence shell rather than according to the octet rule. They only require the s2 orbital filled since they lack p-orbitals.
Thus, The electronic configuration of hydrogen is 1S¹ and He is 1s².
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what is the formula for perchloric acid
The formula for perchloric acid is HClO₄.
Perchloric acid is a strong acid that contains one hydrogen atom, one chlorine atom, and four oxygen atoms. Perchloric acid is a highly corrosive and reactive chemical that is used in a variety of industrial processes, such as rocket fuel production, metal etching, and laboratory reagents.
It is also a common oxidizing agent and can be dangerous if handled improperly, as it can react violently with organic materials and other reducing agents.
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what is the experimental group in the alka-seltzer experiment
The Alka-Seltzer experiment's experimental group is the group of volunteers who are given Alka-Seltzer pills to ingest.
The experiment's goal is to test the hypothesis that Alka-Seltzer pills will shorten the time it takes for stomach discomfort to go away. The control group consists of volunteers who were given a placebo, or a false drug, instead of the Alka-Seltzer pills.
The experimental group is critical to the experiment because it allows for a comparison of the outcomes seen in subjects given Alka-Seltzer pills vs those given a placebo. The hypothesis could not be tested and the results could not be appropriately understood in the absence of an experimental group.
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calculate the mass of oxygen gas required to occupy a volume of 6 l at a pressure of 20.9 kpa and a temperature of 37◦c.
At a pressure pf 20.9 kpa as well as a temperature near 37 °C, the mass liquid oxygen gas needed to fill a volume od 6 l is 1.56G.
Mass, by what name?It all comes together in the celebration of the Eucharist mass, the main act of worship in the Roman Catholic Church. Ite, missa est, the Latin ecclesiastical expression for the congregation's dismissal, is where the word "mass" originates.
How do mass and volume work?A: An object's volume, which is expressed in cubic units, is the space that it takes up in three dimensions. Both cm3 and in3 are examples of cubic units. The quantity of matter in an item is quantified by its mass, on the other hand. How much is a common way of determining mass.
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Matter is classified as a
A.homogeneous or heterogeneous mixture
B.substance or a mixture of substances
C.substance, only
D.mixture of compounds
Matter is classified as a substance or a mixture of substances.
Pure substances and mixtures are the two subgroups of matter. Elements and compounds are formed through the further division of pure substances.
Physically coupled structures known as mixtures can be disassembled into their component parts. One particular sort of atom or molecule makes up a chemical compound.
Complete the photosynthesis reactions by placing the following items as reactants, energy sources, or products of these reactions. Not all labels will be placed.
6CO2 + 6H2O = C6H12O6 + ....
Energy source: ....
The reactants, products and energy sources of the photosynthetic reaction are as follows:
Reactants: carbondioxide and glucoseproducts: glucose and oxygenenergy source: ATPWhat is photosynthesis?Photosynthesis is any process by which plants and other photoautotrophs convert light energy into chemical energy.
Photosynthesis combines carbondioxide and water to produce glucose and oxygen with the dispense of energy.
Carbondioxide and water can be classified as reactants while glucose and oxygen can be regarded as products.
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the term for the branch of science that studies atoms is
The branch of physics known as "atomic physics" focuses on the study of atoms as self-contained systems made up of electrons and nuclei.
In general, the term "atomic physics" refers to the study of the structure of atoms and the interactions between atoms. The arrangement of electrons around the nucleus and the mechanisms by which this arrangement changes are major topics of interest. Unless specifically stated to consist of ions and neutral atoms, the term "atom" is meant to include ions.
Atomic physics is a term that can refer to nuclear energy and nuclear weapons.
Atomic physics, which treats an atom as a system consisting of a nucleus and electrons, differs from nuclear physics, which studies nuclear reactions and the unique properties of atomic nuclei.
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Calculate the mass of iron sulphide produced when 320g of sulphur is reacted with excess iron
The concept stoichiometry is used here to determine the mass of iron sulphide produced. The mass of FeS formed from 320g of sulphur is 878.5 g.
What is stoichiometry?The stoichiometric concept is generally used for the calculations of masses and sometimes the volumes and reactants and products involved in a chemical reaction. The relationship between the amounts of reactants and products can be obtained in a chemical reaction.
Molar mass of 'Fe' = 55.85 g/mol
Molar mass of 'S' = 32 g/mol
The molar mass of FeS = 55.85 + 32 = 87.85 g/mol
The reaction between 'Fe' and 'S' is:
Fe + S → FeS
Here 1 mole of FeS is formed from 1 mole of 'S'.
The amount of FeS formed by 32 g 'S' = 87.85 g
The amount of FeS formed by 320 g of 'S' = (320 × 87.85) / 32 = 878.5 g.
Thus the mass of 'FeS' produced is 878.5 g.
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colligative properties depend only on solute concentration; the identity of the solute is not important. True or False?
The given statement is " colligative properties depend only on solute concentration; the identity of the solute is not important" is true as it will depend on the ratio of the number of the particles of the solute and the solvent in the solution,
The Colligative properties of the solutions are the properties that will depend upon the concentration of the solute molecules or the ions, but it will not upon the identity of solute. The Colligative properties are such as the vapor pressure lowering, the boiling point elevation, the freezing point depression, and the osmotic pressure.
The one of the properties of the solution is the colligative property if it will depends only on the ratio of the number of the particles of the solute and the solvent in the solution.
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how many grams of co are needed to reaxt with an excess of fe2O3
What is the frequency of a sound with a wavelength of 4.22 m and having a wave speed of 12.6 m/s?
The frequency of this sound is 2.86 Hz with a wavelength of 4.22 m and having a wave speed of 12.6 m/s.
What is the wavelength ?Wavelength is the distance between repeating units of a waveform, such as points on a wave or crests and troughs. It is commonly measured in meters. The wavelength is related to the frequency of a wave by the formula wavelength = speed of wave/frequency. The speed of a wave is often determined by the medium it is traveling through; for example, sound waves travel much faster through air than through water. Wavelength is an important factor in determining the properties of a wave, such as its energy, direction, and amplitude.
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