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LTHS: Chemistry
22
2023
Period
Unit Review -Thermochemistry
12.1 I can distinguish between exothermic and endothermic reactions in
terms of
enthalpy.
1. List 4 characteristics of an exothermic process and list 2 examples.
energy
is
a
product
negative (-)
value is
heat energy is released from chen bords
R
E
Rx
E
F/R
2. List 4 characteristics of an endothermic process and 2 examples.
energy
At Valve
is
reactant
is positive (+)
heat energy is
Stored as chem. bonds
Rx 12.3 I can explain how speci fi c heat capacity affects thermal properties
of different
substances.
C
6. What is speci fi c heat capacity?
how much energy is needed to heat
7+
tells
a
Substance
by 1.00c.
7. What does the size of speci fi c heat tell us about a substance?
larger The Speci fi c
The
(higher speci fi c heat means
100g of
hect, The more
energy
it requires to JT.
charges temp slower)
it
12.4 I can perform calculations using the speci fi c heat equation.
8. What is the speci fi c heat of aluminum if the temperature of a 56.8 g
sample of
aluminum is increased by 9.2C when 454 J of heat is added?
9 = mxc
mxdi
9=454 J
m= 56.8g Solid
9 = -4775<
12.
A 20.26 g sample of an unknown solid is heated
to 78.3C and placed into a calorimeter containing
43.83 g of water at 30.7C. If the fi nal temperature of
the solid sample and water is 33.3C, what is the
speci fi c heat of the solid? Use the table to identify the
element.
mxcxo
There have
HO
Substance Speci fi c heat in J/gC
Gold
9 = ?
M-
43.835
4.1845/9C
OT=33,3-30,7-26
0.129
Iron
0.449
Titanium 0.523
C=
Copper 0.385
looks like
Titanium
9=mxcxot
9=43.25g x 4.184 7.6
9
$4775
E+64 Hydrazine (N.H.) reacts with chlorine gas according to the following
equation.
N.H. (1) + 2 Cl (g) - 4 HCl (g) + N (g) = - 420.0
16.
Calculate the change in energy for this reaction under each of the
following
conditions.
a. 25.4 g of hydrazine reacts with excess chlorine.
25.4g Nattyy India
32.065 Malta
b. 1.45 mol HCl is generated.
333 kJ
(333 KT of energy is )
released.
-420.015
X
Ima Norte
1.45 mol Hel
-420.0*5
-152kJ
(152KJ of
energy is
released)
=
4 mol HCI
17.
For the reaction 2Mg (s) + O2(g) 2MgO (s)
AH= 288 kcal.
a. Calculate how many grams of MgO will be produced if 1,356 kcal are
1356kcal
produced.
2m Mgo