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Recent questions in Chemistry
+1
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A chemistry student needs to quantify the amount of iron (II) ions in a sample using colorimetry. The sample was prepared by dissolving a known mass of iron (II) sulfate in water, and the solution was diluted to a known volume. The student needs to determine the concentration of iron (II) ions in the original solution by measuring the absorbance of the sample using a colorimeter, and then using calibration curves to convert the absorbance to concentration. The student also needs to calculate the percentage error of the experiment and suggest ways to improve the accuracy of the results.
asked
Jan 22
in
Analytical Chemistry
by
StephenFrawl
(
220
points)
0
votes
1
answer
81
views
A chemistry student needs to prepare a buffer solution with a pH of 7.2 using acetic acid (CH3COOH) and sodium acetate (CH3COONa). The student has 100 mL of 0.1 M acetic acid and 100 mL of 0.1 M sodium acetate. What volume of each solution do they need to mix to prepare the desired buffer solution with a total volume of 500 mL?
asked
Jan 22
in
Chemical reactions
by
ArnetteLunds
(
430
points)
0
votes
1
answer
69
views
A chemistry student needs to prepare a buffer solution with a pH of 5.2 using acetic acid (CH3COOH) and sodium acetate (NaC2H3O2). The student has 10 mL of 0.15 M acetic acid and 15 mL of 0.20 M sodium acetate. What volume of water should the student add to make the desired buffer solution?
asked
Jan 22
in
Chemical reactions
by
Francesca85W
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330
points)
0
votes
1
answer
105
views
A chemistry student needs to prepare a buffer solution of pH 5.0 using acetic acid and acetate ions. If the student has 0.3 M acetic acid and 0.2 M acetate ions, what volume of acetic acid and acetate ions should he/she mix to prepare a solution with a total volume of 500 mL?
asked
Jan 22
in
Chemical reactions
by
AbeTryon7251
(
450
points)
0
votes
1
answer
89
views
A chemistry student needs to predict the products of a reaction between aluminum and sulfuric acid. What chemical equation represents this reaction and what are the names and states of the products formed?
asked
Jan 22
in
Inorganic Chemistry
by
LeopoldoConn
(
460
points)
0
votes
1
answer
48
views
A chemistry student needs to identify an unknown compound using mass spectrometry. The compound has a molecular ion peak at m/z 120 and four major fragment ions at m/z 91, 77, 63, and 45. What is the molecular formula of the unknown compound?
asked
Jan 22
in
Analytical Chemistry
by
ChristianFar
(
290
points)
0
votes
1
answer
80
views
A chemistry student needs to identify an unknown compound found at a crime scene using mass spectrometry. The compound has a molecular weight of 286 g/mol and the mass spectrum shows a strong peak at m/z = 180 and a weaker peak at m/z = 148. What is the possible molecular formula of the unknown compound?
asked
Jan 22
in
Analytical Chemistry
by
FrancescoGui
(
130
points)
0
votes
1
answer
60
views
A chemistry student needs to find the rate of a chemical reaction for a given set of concentrations and time, given the following reaction: 2H2 (g) + O2 (g) -> 2H2O (g)If the initial concentrations of H2 and O2 are 0.5 M and 0.2 M, and the reaction rate is 0.12 M/s, what is the concentration of H2O after 10 seconds?
asked
Jan 22
in
Chemical reactions
by
WFBMonty0506
(
230
points)
0
votes
1
answer
79
views
A chemistry student needs to find the percent composition of a compound with the empirical formula CCl. The compound has a molar mass of 98.96 g/mol. What is the percent composition of this compound?
asked
Jan 22
in
Inorganic Chemistry
by
DorieBarth39
(
510
points)
0
votes
1
answer
54
views
A chemistry student needs to determine the standard enthalpy change for the formation of NH3(g) from its constituent elements, using Hess's Law calculations. The student is given the following information:ΔHf°(NH3) = -46 kJ/molΔHf°(N2) = 0 kJ/molΔHf°(H2) = 0 kJ/molΔH298°(N2H4) = 95 kJ/molΔHf°(N2H4) = 50 kJ/mol2NH3(g) + N2H4(l) → 3N2(g) + 4H2(g)What is the value of ΔHf° for NH3, based on the above data?
asked
Jan 22
in
ThermoChemistry
by
ClairePresto
(
230
points)
0
votes
1
answer
34
views
A chemistry student needs to determine the specific heat capacity of a metal block. The student has the following information: the mass of the block is 75 g and its initial temperature is 25°C. The student heats the block to 100°C, and calculates that it absorbed 1500 J of heat during this process. What is the specific heat capacity of the metal block?
asked
Jan 22
in
ThermoChemistry
by
GuillermoJep
(
410
points)
0
votes
1
answer
61
views
A chemistry student needs to determine the rate law for the reaction between hydrogen peroxide and iodide ion in the presence of an acid catalyst. Using experimental data, what is the order of the reaction with respect to hydrogen peroxide, iodide ion, and acid? Write the rate law equation for this reaction.
asked
Jan 22
in
Chemical kinetics
by
JuniorReyes
(
330
points)
0
votes
1
answer
58
views
A chemistry student needs to determine the rate constant for the reaction between hydrochloric acid and sodium thiosulfate. If the initial concentration of hydrochloric acid is 0.1 M, the initial concentration of sodium thiosulfate is 0.05 M, and the initial rate of the reaction is 8.7 x 10^-5 mol/L.s, what is the rate constant for this reaction?
asked
Jan 22
in
Chemical kinetics
by
EloisaStrehl
(
370
points)
0
votes
1
answer
45
views
A chemistry student needs to determine the rate constant (k) and the initial rate (vo) of an enzymatic reaction that follows Michaelis-Menten kinetics. The reaction involves the conversion of substrate A to product B in the presence of an enzyme that is inhibited by a competitive inhibitor. The student should also calculate the inhibition constant (Ki) of the inhibitor and determine the type of inhibition (competitive, non-competitive or uncompetitive).
asked
Jan 22
in
BioChemistry
by
TriciaMccomb
(
390
points)
0
votes
1
answer
86
views
A chemistry student needs to determine the precipitate formed when 50 mL of 0.2 M silver nitrate solution is mixed with 75 mL of 0.1 M potassium chloride solution. What is the mass of the precipitate formed and what is the percent yield of the reaction?
asked
Jan 22
in
Chemical reactions
by
JeremiahMcNe
(
150
points)
0
votes
1
answer
10
views
A chemistry student needs to determine the pH of an unknown solution using a pH meter. The student is given the following equipment: pH meter, reference electrode, and a container for the solution. The student should describe the steps needed to measure the pH of the solution and explain the significance of the obtained pH value.
asked
Jan 22
in
Analytical Chemistry
by
DeboraPrenti
(
250
points)
0
votes
1
answer
69
views
A chemistry student needs to determine the pH of a solution using a pH meter. The student has to prepare a buffer solution of pH 7.0 using 0.1M acetic acid and 0.1M sodium acetate. The student is then required to measure the pH of the prepared buffer solution using a pH meter and record the observations. Finally, the student has to compare the pH value obtained by the pH meter with the calculated pH value of the prepared buffer solution and explain any deviations observed.
asked
Jan 22
in
Analytical Chemistry
by
Steve6884784
(
430
points)
0
votes
1
answer
70
views
A chemistry student needs to determine the percentage of iron (Fe) present in a given iron ore sample using gravimetric analysis. The student is provided with the mass of the iron ore sample and a standardized solution of potassium dichromate (K2Cr2O7) to use for the analysis. What is the percentage of iron (Fe) in the given iron ore sample?
asked
Jan 22
in
Analytical Chemistry
by
MichaelaBrad
(
410
points)
0
votes
1
answer
42
views
A chemistry student needs to determine the percentage of calcium carbonate (CaCO3) present in a mixture of calcium carbonate and calcium phosphate. The student has the following information: A 1.00-gram sample of the mixture was dissolved and reacted with excess hydrochloric acid (HCl), producing 0.236 grams of carbon dioxide (CO2) gas. The balanced chemical equation for the reaction is: CaCO3 + 2HCl → CaCl2 + CO2 + H2O. The student also knows that the molecular weight of CaCO3 is 100.09 g/mol and that of Ca3(PO4)2 is 310.18 g/mol. What is the percentage of calcium carbonate in the mixture?
asked
Jan 22
in
Analytical Chemistry
by
GeraldineLam
(
310
points)
0
votes
1
answer
62
views
A chemistry student needs to determine the percent composition of nitrogen (N) in a sample of an unknown organic compound. Using elemental analysis, the student determines the mass of the sample to be 0.254 g and the mass of the products after combustion to be 0.727 g of CO2 and 0.298 g of H2O. What is the percent composition of nitrogen in the sample?
asked
Jan 22
in
Analytical Chemistry
by
JanBallow529
(
150
points)
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