Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
11 Cards in this Set
- Front
- Back
|
Give an example of an endothermic reaction |
Thermal decomposition: Heat must be supplied to cause the compound to decompose. |
|
|
Give an example of an exothermic reaction |
Burning fuels: Gives out a lot of heat. |
|
|
Is bond breaking an exothermic or endothermic reaction? |
Bond breaking is an endothermic reaction because energy must be supplied to break existing bonds. |
|
|
Give the formula that you would use to find the amount of energy transferred to the water in a calorimetric experiment. |
Energy transferred (j) = Mass of water (g) x Specific heat capacity of water (=4.2j/g'c) x temperature change ('c) |
|
|
Give three things you should do in order to make sure a calorimetric experiment is as accurate as possible. |
1. Use the same apparatus. 2. Use the same amount of water. 3. The water should start and finish at the same temperature each time. |
|
|
How might you measure the rate of reaction between calcium carbonate and hydrochloric acid? |
By measuring the change in mass or the volume of gas given off. |
|
|
Explain how increasing collision frequency affects the rate of a chemical reaction. |
Reactions happen if particles collide. If you increase the number of collisions, the reaction happens quicker. |
|
|
What four things affect the rate of reaction? |
1. Increasing the temperature means the particles are going faster and have more energy. 2. Increasing the concentration (or pressure) means the particles are more crowded together. 3. Small solid particles (or more surface area) means other particles can get to it easier. 4. A catalyst increase the number of successful collisions. |
|
|
Why do gases react faster when they're under higher pressure? |
Increasing the pressure means the molecules are more crowded, so the frequency of the collisions increase. |
|
|
Why do fine combustible powders sometimes explode? |
Fine combustible powders dispersed in the air burn very fast because they have such a big surface area. |
|
|
A piece of magnesium is added to a dilute solution of hydrochloric acid, and hydrogen gas is produced. The experiment is repeated with a more concentrated hydrochloric acid. How can you tell from the experiment which concentration of acid produces a faster rate of reaction? |
When using the concentrated acid it will take less time to produce the same amount of gas than when using the dilute acid - the rate of reaction is faster. The slope of the graph (time vs volume of gas) will be steeper for the acid which produces the faster rate of reaction. |
