Question

A) How much heat must be absorbed by a 23.0 g sample of water to raise its temperature from 30.0 ∘C to 50.0 ∘C? (For water, Cs=4.18J/g∘C.)

Express your answer to three significant figures and include the appropriate units.

ΔErxn =	nothing	kJ/mol

B) anganese reacts with hydrochloric acid to produce manganese(II) chloride and hydrogen gas.

Mn(s)+2HCl(aq) → MnCl2(aq)+H2(g)

You may want to reference (Page 271) Section 6.7 while completing this problem.

Part A

When 0.635 g Mn is combined with enough hydrochloric acid to make 100.0 mL of solution in a coffee-cup calorimeter, all of the Mn reacts, raising the temperature of the solution from 23.7 ∘C to 28.7 ∘C.
Find ΔHrxn for the reaction as written. (Assume that the specific heat capacity of the solution is 4.18 J/g∘C and the density is 1.00 g/mL.)

Express your answer using three significant figures.

c) block of copper of unknown mass has an initial temperature of 63.2

∘C. The copper is immersed in a beaker containing 97.7 g of water at 22.6 ∘C. When the two substances reach thermal equilibrium, the final temperature is 24.2 ∘C. What is the mass of the copper block? Assume that Cs,H2O=4.18J/(g⋅∘C) and Cs,Cu=0.385J/(g⋅∘C).

Express the mass to two significant figures and include the appropriate units.

d) A cylinder equipped with a piston expands against an external pressure of 1.39

atm . If the initial volume is 0.450 L and the final volume is 1.235 L , how much work (in J) is done?

Express the energy to three significant figures and include the appropriate units.

Answer 1