Vocab
A reaction is one that gives off heat
Exothermic
Convert 475 J to cal
114 cal
How much heat (in joules) is needed to raise the temperature of 355 g of ethanol (c = 2.4 J/g°C) by 63°C?
54,000 J
How many moles of water are produced from the following reaction, when 275 kJ of energy is given off?
4 NH3 + 3 O2 -> 2 N2 + 6 H2O ΔH = -1530 kJ
1.08 mol H2O
How much energy is produced when 93.5 grams of oxygen reacts with 13.2 g hydrogen in the following reaction?
2 H2 + O2 -> 2 H2O ΔH = -572 kJ
O2: -1670 kJ
H2: -1870 kJ
A reaction is one that absorbs heat
Endothermic
Convert 270 cal to J
1100 J
How many kilojoules of heat are required to heat 2550 grams of water from 17.5°C to 100.0°C?
879 kJ
How many grams of magnesium sulfate would be produced from the following reaction if 176 kJ of energy is absorbed by the reaction?
Al2(SO4)3 + 3 MgI2 -> 2 AlI3 + 3 Mg(SO4) ΔH = +722
88.0 g Mg(SO4)
How much energy will be given off from the following reaction, if 3.0g of sodium reacts with 1.2g of nitrogen in the following reaction?
6 Na + N2 -> 2 Na3N ΔH = - 42.7 kJ
Na: -2.8 kJ
N2: -0.61 kJ
The energy used or produced during a chemical reaction
Enthalpy
Convert 1420 J to kJ
1.42 kJ
What mass of iron (c = 0.11 cal/g°C) would need 875 cal of energy in order to raise its temperature by 3.5°C?
2300 g
The combustion of ethene, C2H4, is an exothermic reaction. Use the information below to determine the amount of energy given off when 2.3 moles of ethene is combusted.
C2H4 + 3 O2 -> 2 CO2 + H2O ΔH= - 1390 kJ
-3200 kJ
What is the maximum amount of energy that could be produced from the reaction of 85.0 grams of Aluminum with 95.0 grams of oxygen, according to the following reaction?
4 Al + 3 O2 -> 2 Al2O3 ΔH = -3352 kJ
Al: -2640 kJ
O2: -3320 kJ
______ of a substance tell how much energy is needed to raise the temperature of 1 gram of that substance by 1°C.
Specific Heat
Convert 10.1 kcal to J
42,200 J
What is the change in temperature of a sample of magnesium (c = 0.24 cal/g°C), if 1835 cal is added to 612 g of magnesium?
12 °C
How many grams of carbon dioxide would be produced from the following reaction, if 175 kJ of energy is given off?
2 CO + O2 -> 2 CO2 ΔH = -566 kJ
27.2 g CO2
How much heat will be transferred when 0.54g of sulfur reacts with 0.54g of oxygen to produce sulfur trioxide according to the following reaction:
2 S + 3 O2 -> 2 SO3 + 790kJ
S: -6.7 kJ
O2: -4.4 kJ
The amount of energy required to raise the temperature of 1 gram of pure water by 1 degree C is exactly equal to
1 calorie
Convert 23.1 kcal to kJ
96.6 kJ
What is the final temperature of a sample of magnesium (c = 0.24 cal/g°C), if 1835 cal is added to 612 g of magnesium at an initial temperature of 19.3°C?
32 °C
How much heat, in kilojoules, is needed to produce 1850 grams of ammonia (NH3), according to the following reaction?
2 N2 + 6 H2O -> 4 NH3 + 3 O2 ΔH = + 1530 kJ
41,500 kJ
How much heat will be absorbed when 38.2 g of bromine reacts with 12.4g of hydrogen according to the following equation?
H2 + Br2 + 72.80 -> 2HBr
Br2: 17.4 kJ
H2: 447 kJ