Unit 7 CHEM Assignment : {ATTN- chemtutor} Please answer the attached..
{ATTN- chemtutor} Please answer the attached..
3) The vaporization of diatomic bromine (Br2) from a liquid to a gaseous state requires 7.4
kcal/mol.
a) What is the sign of delta H for this phase change?
b) How many kilocalories are needed to vaporize 2.5 moles of Br2?
c) How many kilocalories are needed to evaporate 120 grams of Br2?
4) Converting liquid water to solid ice releases 1.44 kcal/mol.
a) What is the sign of delta H for this process?
b) How many kilocalories are released by freezing 3.25 moles of water?
c) How many kilocalories are absorbed by melting 50 grams of ice?
5) Explain how the sign of the free-energy change within a reaction is related to the spontaneity
of the reaction? In your explanation, be sure to explain the terms "free-energy" and
"spontaneity."
6) Is it possible for a reaction to be spontaneous yet endothermic? Explain.
7) Explain two reasons why increasing temperature increases the rate of a reaction.
8) For the production of ammonia (NH3) from its elements, delta H = -22 kcal/mol.
a) Is this process endothermic or exothermic? Explain.
b) How many kilocalories are involved in the production of 0.65 mol of ammonia?
9) Consider the following reaction:
H2 (g) + ½O2 (g) ? H2O(l) + 285.8 kJ
a) In 2-3 well developed sentences, explain the heat of formation for this reaction.
b) How many kilocalories would be released by the formation of 40 grams of water? Explain.
10) The heat of vaporization of diatomic chlorine gas (Cl2) is 4.88 kcal/mol. How much heat is
released with 15 grams of Cl2 gas liquifies?
11) Calculate the heat of vaporization of an unknown substance "X", if 5.0 grams of "X" absorbs
1250 calories of heat in changing from a liquid into a gas.
12) Explain each variable in the specific heat formula
"Q=cm(delta)T".
13) In one well-developed paragraph and in your own words, explain Hess's Law. Include an
example to illustrate your explanation.
14) In one well-developed paragraph and in your own words, explain the Law of Conservation of
Matter. Include an example to illustrate your explanation.
15) In one well-developed paragraph and in your own words, explain the Law of Increased
Entropy. Include an example to illustrate your explanation.
16) In one well-developed paragraph and in your own words, explain the Law of Absolute Zero.
Include an example to illustrate your explanation.