# Gas Laws & Heat Of Reaction

1.

For the reaction

2 NO(g) + O2(g) -->2 NO2(g)

deltaH = -126.0 kJ at 25C.

(a) Calculate the amount of heat transferred when 333 g of NO(g) reacts with O2(g) at 25C and 1 atm.

(b) Does this heat flow into the system or does it flow to the surroundings?

(c) Is this reaction exothermic or endothermic?

2.

If 8675 J of heat flows into 135.0 g of water initially at 20.0C, find the final temperature of

the water. The specific heat of water is 4.18 J g^-1 K^-1.

3.

Find the molecular weight of a gas if 22.24 g of the gas in a 7045 cm^3

container at 20°C exerts a pressure of 698 torr.

CONSTANTS

R = 0.08206 L atm mol^-1 K^-1

1 atm = 760 torr

c = 3.00 x 10^8 m/s

h = 6.63 x 10^-34 J . s

4.

Calculate deltaH at 25C is -1790 kJ for the reaction

C3H6O(l) + 4O2(g) -->3 CO2(g) + 3 H2O(l)

Given these f deltaH values at 25C: -394 kJ/mol for CO2(g), -286 kJ/mol for H2O(l), and 0 for

O2(g), find f deltaH for C3H6O(l).

5.

What volume of H2(g) at 27C and 1.08 atm is produced when

45.3 g of Al reacts as follows:

2Al + 6HNO3(aq) --> 2Al(NO3)3 + 3H2

#### Solution Preview

1.

For the reaction

2 NO(g) + O2(g) 2 NO2(g)

H= -126.0 kJ at 25C.

(a) Calculate the amount of heat transferred when 333 g of NO(g) reacts with O2(g) at 25C and 1 atm.

The molar amount of NO: 333/30.01=11.0963 mol

Heat produced: 126.0/2*11.0963=699.07 kJ

(b) Does this heat flow into the system or does it flow to the surroundings?

Since delta H is negative, it flows to the surroundings.

(c) Is this reaction exothermic or ...

#### Solution Summary

The great laws and heat of reactions are examined.