Changes of State
Heat Energy Q
Heat Energy Q
Potential Energy Graphs
Random
100
All matter exists in three states which are...
What is solids, liquids, and gases.
100

What is Specific Heat?

The  amount of thermal energy required to increase the temperature of 1kg of a material by 1°C.

100

Which of the following is NOT true about heat? 

A. Heat moves from hot to cold                                B. Heat is a form of energy                                        C. Heat cannot be transferred                                 D. Heat makes molecules speed up 

c

100

A candle (system) loses 30 J of heat energy, how much energy is gained by the surroundings?

30 J

100

What does the law of conservation of energy state?

Energy cannot be created or destroyed only transferred. 

200
The physical change from one state of matter to another is called a ___________________.
What is change of state.
200

A high specific heat means...

It requires more energy to change temperature

200

Object A has a specific heat of 4.45 J/g⁰C and object B has a specific heat of 1.82 J/g⁰C. Which object will heat up faster?

Object B, it has a lower specific heat

200

On a potential energy diagram, the products are lower in potential energy than the reactants. Is this reaction endothermic or exothermic?

Exothermic

200

What does a negative ΔH (heat of reaction)indicate?
 

Energy was released during the chemical reaction. It is exothermic. 
300
Matter will change from one state to another if thermal energy is ______________ or ______________.
What is absorbed or released.
300

How many Joules of energy are required to change 10 grams of liquid water from 20 °C to 90 °C? Specific heat of liquid water is 4.18 J / g °C.

2800 J

300

When a  piece of aluminum foil is taken out of the oven and cools from 100° to 50°, What is the change in temperature or ΔT?

50°

300

On a potential energy diagram, the vertical distance from reactants to the high point is labeled. What is this energy called?

Activation energy

300

Is photosynthesis an endothermic or exothermic reaction? Explain

6CO2 + 6H2O + light -> 6O2 + C6H12O6

endothermic reaction since heat is on the reactant side 

400
Freezing occurs when a substance ____________ thermal energy.
What is loses.
400

Which of the following best explains why the sand at the beach is hotter than the water?                             a) There is more sand than water at the beach.         b) Sand has a lower specific heat than water.              c) Sand has a higher specific heat than water.           d) There is more water than sand at the beach.

b

400

Graphite has a specific heat of 0.709 J/g⁰C. If a 20 gram piece of graphite is cooled from 38⁰C to 18⁰C, how much energy was lost by the graphite?

283.6 J

400

A reaction’s reactants are at 220 kJ, the peak (high point) is at 360 kJ, and products are at 140 kJ. What is the activation energy?

A. 120 kJ B. 140 kJ C. 220 kJ D. 360 kJ  

360 kJ - 220 kJ = 140 kJ

400

Room temperature water is 70 degrees F. What does the temperature tell us about atom vibrations?

Temp measures the average kinetic energy (vibrations).

500
When gas loses a sufficient amount of thermal energy, it will change into a ______________.
What is liquid.
500

A 2.0kg aluminium cube, is left in the sunlight and its temperature rises from 20∘C to 60∘C. How much energy has been transferred into the cube?
Aluminium has a specific heat capacity of 900J/(kg∘C).

720000J

500

How much energy is needed to raise the temperature of 0.20kg of cooking oil by 50∘C, if the specific heat capacity of this oil is 1800J/(kg∘C)?

18000 J

500

Using the values reactants 220 kJ and products 140 kJ, what is ΔH (heat of reaction)?


A. +80 kJ B. −80 kJ C. +360 kJ D. −360 kJ

140kJ - 220kJ = -80kJ

500

When does kinetic energy remain constant in an energy phase diagram?

During phase changes 

M
e
n
u