Physical Chemistry Answers

5.0g of solid zinc carbonate are heated to produce oxide and carbon dioxide.

Right the balance equation?

2.48g of hydrated copper(ii)chloride (CuCl2.xH2O) were heated to constant mass.

1.96g of anhydrous copper(ii)chloride were obtained.

determine the value of x in CuCl2.xH2O.(AO2)

sodium azide (Na3N) decomposes on heating to form sodium and nitrogen gas.

2Na3N--> 6Na+N2

1.35g of sodium nitride were heated.

a) calculate the mass of sodium formed on complete decomposition of the sodium nitride. give your answer to 3 significant figures.(AO2)

b)calculate the volume of nitrogen gas (in cm^3)produced on complete decomposition of 1.35g of sodium nitride at 320K and 110kpa. the gas constant R= 8.31JK^-1 mol^-1.

give your answer to 3 significant figures. (AO2)

five indigestion tablets containing calcium carbonate with a total mass of 2.50g were added to 50.0cm^3 of1.00mol dm^-3 hydrochloric acid.

CaCO3+2HCl--> CaCl2+CO2 +H2O

after reaction the solution was transferred to a 250cm^3 volumetric flask and the volume made up to 250cm^3 using deionised water. 25.0cm^3 samples of the solution were titrated against 0.126mol dm^-3 sodium hydroxide solution.

NaOH+HCl--> NaCl+H2O

the average titre was 11.30cm^3.

a) calculate the mass of calcium carbonate (in grams) in the five tablets.

give your answer to 3 significant figures.(AO2)

b) calculate the percentage of calcium carbonate in the tablets.(AO2)

C_(s) + CO_{2 (g)} ↔ 2CO_(g)

ΔH is greater than zero. If ΔH is assumed to be independent of temperature, which statement about the percentage yield of CO_(g) is true?

A.

It increases when the total pressure of the reaction system increases

B.

It increases as the amount of C_(s) increases

C.

It increases as the temperature increases

D.

It decreases when the temperature increases

For the reaction shown below

O_3(g) → 3/2 O_2(g)

at 298 K, ΔG^o = -163 kJ/mol. The value of the equilibrium constant, K_p, for this reaction is?

To 5.0 L ideal gas, 1.0 kJ of heat is added. The gas expands against a constant external pressure of 1.0 bar to a final volume of 8.0 L. What is the change internal energy for the gas (1.0 L.bar = 0.10 kJ)