Practice Exercise 2 Hydrogen peroxide can decompose to water

Practice Exercise 2 Hydrogen peroxide can decompose to water a the reaction 2H2O2(1)2H20(I) + 02(g) AH-1 kj Calculate the quantity of heat released when 5.00 g of H202(1) decomposes at constant pressure.

Solution

Q1)

From the given equation

when 2 moles of H2O2 ( 2 x 34 g) is decomposed , the heat liberated = 196 kJ

When 5 go f H2O2 is decomposed , th eheat liberated = 5g x 196kJ /2x34 g

= 14.411 kJ

Q2) Cu, Ag, Au

0.385,0.233 and0.129 J/g-K are the specific heats.

Copper silver and gold are in the same group one below another.

Thus as the atomic weight increases both specific heat and molar heat capacity decrease down the group.

Molar heat capacity decreases

specific heat capacity decreases with increase in atomic weight.