Energy level diagrams

Energy level diagrams

Which reaction is exothermic?

1. 
2. 
3. 
4. 

Which one of these reactions releases energy?

1. carbon dioxide + water → glucose + oxygen
2. carbon + oxygen → carbon dioxide
3. copper carbonate → copper oxide + carbon dioxide

carbon + oxygen → carbon dioxide
If the reactants have 100 J of energy
and the products have 80 J How much energy is released?

1. 200 J
2. 2000 J
3. 20 J
4. 2 J

carbon + oxygen → carbon dioxide
If the reactants have 100 J of energy
and the products have 90 J How much energy is released?

1. 20 J
2. 10 J
3. 0.10 J
4. 90 J

carbon + oxygen → carbon dioxide
If the reactants have 1000 J of energy
and the products have 190 J How much energy is released?

1. 110 J
2. 190 J
3. 910 J
4. 810 J

In an exothermic reaction the products have

1. less energy than the reactants.
2. more energy than the reactants.

If the products have less energy than the reactants.

1. The reaction is endothermic
2. The reaction is exothermic

What is an exothermic reaction?

1. Occurs in cold environments
2. Releases heat energy
3. Results in temperature decrease
4. Absorbs heat energy

Which process is endothermic?

1. Photosynthesis
2. Respiration
3. Neutralization
4. Combustion

What happens to energy in exothermic reactions?

1. Energy is released
2. Energy remains constant
3. Energy is absorbed
4. Energy is created

Which of these is exothermic?

1. Evaporating water
2. Burning wood
3. Dissolving salt
4. Melting ice

What is a characteristic of endothermic reactions?

1. Temperature decreases in surroundings
2. Releases light
3. Forms gas only
4. Temperature increases in surroundings

If 10 J of energy is taken in and the reactants have 50 J of energy how many J does the products have?

1. 6 J
2. 10 J
3. 60 J
4. 50 J

If 20 J of energy is taken in and the reactants have 50 J of energy how many J does the products have?

1. 70 J
2. 20 J
3. 60 J
4. 50 J

If 210 J of energy is taken in and the reactants have 150 J of energy how many J does the products have?

1. 36 J
2. 150 J
3. 350 J
4. 360 J

Endothermic

Exothermic

Endothermic

What characterizes an exothermic reaction?

1. Releases energy to the surroundings
2. Absorbs energy from the surroundings

In energy level diagrams, which direction is energy flow for exothermic reactions?

1. Downward
2. Upward

What happens to the products' energy in exothermic reactions?

1. Lower than reactants' energy level
2. Higher than reactants' energy level

Which graph represents an exothermic reaction?

1. Energy level decreases from reactants to products
2. Energy level increases from reactants to products