Chemistry 3 Unit 3

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What is a calorimeter?

This is a process used to measure the amount of energy released even substances burn
Give an example of simple calorimeter

Heating water in a glass beaker/ metal container
What does the temperature rise depend on when water is heated?

The temperature rise depends on the amount if energy released
How is the amount of energy transferred calculated?
Q = mc?T
- Q = The amount if energy transferred in Joules J
- M = mass of water in grams g
- C = the specific heat capacity J/g•c
- ?T = Temperature change •c
Why do simple calorimeters not give accurate results?

Much of the energy is used to heat the surroundings
How can we reduce the energy transfer to the surroundings?

Do the reaction in an insulated container
How are neutralisation and displacement reactions calculated?
Q = mc?T
- Q = The amount if energy transferred in Joules J
- M = mass of water in grams g
- C = the specific heat capacity J/g•c
- ?T = Temperature change •c
If we assume the solutions behave like water what is the mass and specific heat capacity?

1cm''' of a solution is 1g and the specific heat capacity of the solution is 4.2J/g•c
What must happen to reactants for the reaction to take place?
- During a chemical reaction bonds in the reactant must be broken for the reaction to happen
- Energy is released when bonds are formed
What is the activation energy?

This is the minimum energy required for the reaction to happen
Draw an energy level diagram for an exothermic reaction
- Reactant
- _______
- ????|
- ????| Energy released
- ????|
- ????|______
- ????Products
Draw an energy level diagram showing the activation energy as well as the use of catalyst for an exothermic reaction
- ????Activation energy
- ????? ^
- ?????| |
- Reactant? |^| catalyst
- _________|?|
- ?????? |
- ?????? |_____
- ??????Products
What does a catalyst do to the reaction and activation energy?

Catalysts increase the rate of reaction and lower the activation energy
In an exothermic reaction what is the relationship between the energy released from forming bonds and the energy needed to break bonds?

In an exothermic reaction, the energy released from forming bonds, is greater than the energy needed to break bonds
In an endothermic reaction what is the relationship between the energy released from forming bonds and the energy needed to break bonds?

In an endothermic reaction, the energy needed to break bonds, is greater than the energy released from forming bonds
What's the advantages of using hydrogen for fuel?
- Hydrogen can be produced from renewable sources
- Hydrogen burns easily and releases a large amount of energy per gram
- It doesn't produce Carbon dioxide when burned
What is the disadvantage of using hydrogen for fuel?
- Supply, storage, safety problems
- It's costly to match the performance, convenience and cost of petrol and diesel vehicles

Author

Rvynvega

220120

Card Set

Chemistry 3 Unit 3

Description

Energy calculations

Updated

2013-05-18T12:43:13Z

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