1. An ice pack makes the surroundings cold. This is an example of...
an endothermic reaction
an exothermic reaction
a system in equilibrium
a system that releases heat
2. Which of the following needs to remain constant in order for a calorimeter
to work effectively?
temperature
time
pressure
none of the above
3. Which of the following graphs shows an exothermic reaction? How do you know?
A because the ∆H value is positive
B because the ∆H value is negative
A because the ∆H value is negative
B because the ∆H value is positive
4. A 500g piece of Aluminum has a temperature increase of 7 degrees. The specific heat of Aluminum is 0.900 J/gC. If you were using q = m c ∆T to find the amount of heat produced, which value would you plug in for "m"?
500 g
0.900 J/gC
3150 J
7 degrees
5. What is a potential energy diagram used for?
To show how much kinetic energy is released in a chemical reaction
To show the change in potential energy of the reactants and the products of a reaction
To show the potential energy in the surroundings versus the system
To show the kinetic energy versus the potential energy of the reactants only
6. For the formula: q = m c ∆T, What does the c stand for?
heat
mass
specific heat
change in temperature
7. For the formula: q = m c ∆T, What does the ∆T stand for?
heat
mass
specific heat
change in temperature
8. Water has a relatively high specific heat capacity. This means that...
it takes a lot of heat energy to increase its temperature.
it is easier to heat up and does not take much energy to do so.
it does not change temperature.
it does not absorb heat energy very well.
9. The amount of energy that is required to raise the temperature of one gram of pure substance or material by one degree Celsius (1°C) is called __________.
enthalpy
specific heat
mass
temperature
10. Nitrogen reacts with hydrogen to produce ammonia according to the following equation: N2(g)+3H2(g)→2NH3(g); ΔH=-92 kJ mol-1 The energy change for this reaction is best described as...
exothermic, because the energy of the bonds in the products is greater than the energy of the bonds in the reactants
endothermic, because the energy of the bonds in the products is greater than the energy of the bonds in the reactants
exothermic, because the energy of the bonds in the products is less than the energy of the bonds in the reactants
endothermic, because the energy of the bonds in the products is less than the energy of the bonds in the reactants
11. According to the following chart that shows specific heat capacity values, which of the following substances would heat up the fastest?
Aluminum
Copper
Gold
Water
12. What is the name of the device that is used to measure the amount of heat absorbed or released during chemical reactions?
Heat tranfser
Heat of formation
Specific heat
Calorimeter
13. In which of the following scenarios would water molecules have the highest average kinetic energy?
Liquid water at 90 °C
Steam at 200 °C
Ice at 0 °C
Liquid water at 89 °C
14. If two objects have different temperatures, heat will flow from the warmer object to the cooler one UNTIL ____________
one object freezes
both objects increase in temperature
they both have the same temperature
one reaches a temperature of zero
15. For a skillet, used for cooking food, do you want a high or low specific heat? Why?
High, so that it will need more energy to heat up.
Low, so that it will change temperature quickly.
The type of skillet does not affect how fast it heats up.
Need more information to determine.
16. A metal cube at temperature of 10°C immersed in a liquid at temperature of 70°C. What is the temperature of the metal cube when thermal equilibrium is achieved between the cube and the liquid?
Same as the room temperature
Less than 10°C
Between 10°C and 70°C
More than 70°C
17. Heat energy moves from __________ to __________ objects.
cooler, warmer
small, large
large, small
warmer, cooler
18. Using q = m c ∆T, calculate the energy (q) released when 240 g of iron is cooled by 65 °C. The specific heat (c) of iron= 0.452 J/g°C
-7051.2 J
-15,600 J
-108.48 J
-29.38 J
19. Explain how calorimetry works. What is the process? How is the data used?
20. When thinking about flow of heat, describe what would happen if you submerged a scorching hot piece of iron metal in a bath of cool water. What happens to the water? What happens to the iron? Explain why.
21. In your own words, explain how having an understanding of the chemistry behind energy is useful when looking at the calories in different food items.