Recent questions in Chemistry

0 votes

1 answer 8 views

A chemistry student wants to buffer a solution with a pH of 4.5. The student adds 0.1 mol of a weak acid buffer to 0.1 mol of a conjugate base. Taking the pKa value of the buffer into consideration, determine how much stronger an acid in the same buffer system would need to be added to the solution to shift the pH from 4.5 to 4.0, assuming temperature and pressure are constant.

asked Jan 22 in Chemical equilibrium by NikiCoombs07 (590 points)

0 votes

1 answer 72 views

A chemistry student wants to analyze a sample of wastewater from a local factory. They want to know the concentration of the pollutants from the wastewater before releasing it into the environment. The sample is collected in a 500 mL container. After performing the required tests, the student determines that the total dissolved solids (TDS) in the sample are 750 mg/L, and the concentration of NaCl in the sample is 150 mg/L. Calculate the mass of TDS and NaCl in the sample.

asked Jan 22 in Analytical Chemistry by JensKaye7769 (470 points)

0 votes

1 answer 48 views

A chemistry student synthesized 25 grams of aspirin theoretically, but only obtained 20 grams practically in the lab. Calculate the percent yield of aspirin.

asked Jan 22 in Chemical reactions by LawannaPraed (450 points)

0 votes

1 answer 7 views

A chemistry student performed a reaction that produced 2.0 grams of product. The theoretical yield for this reaction is 2.5 grams. Calculate the percent yield for this reaction.

asked Jan 22 in Chemical reactions by Douglas62730 (610 points)

+1 vote

1 answer 64 views

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 PasqualePurv (680 points)

0 votes

1 answer 69 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 DomingoMarce (750 points)

0 votes

1 answer 58 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 EarnestineGo (590 points)

0 votes

1 answer 78 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 EileenRubin0 (690 points)

0 votes

1 answer 75 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 MahaliaCampb (430 points)

0 votes

1 answer 45 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 JennieCasas0 (470 points)

0 votes

1 answer 68 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 ElaneLavarac (590 points)

0 votes

1 answer 49 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 PatriceBayle (370 points)

0 votes

1 answer 73 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 JuliShull51 (370 points)

0 votes

1 answer 35 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 PreciousS02 (710 points)

0 votes

1 answer 31 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 ElliotTurnbu (450 points)

0 votes

1 answer 58 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 MargretSuggs (390 points)

0 votes

1 answer 54 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 Marsha834102 (390 points)

0 votes

1 answer 6 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 MarinaWsq125 (550 points)

0 votes

1 answer 70 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 AnnabelleHed (550 points)

0 votes

1 answer 8 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 KAULeora045 (510 points)

Page:

« prev
1
...
206
207
208
209
210
211
212
213
214
...
234
next »

Recent questions in Chemistry

Categories