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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

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Solution Preview

1.

For the reaction

2 NO(g) + O2(g) 2 NO2(g)
H= -126.0 kJ at 25C.

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

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