C3 1-8 Flashcards
What is reaction time?
the time taken between a reaction starting and stopping.
Give an example of a fast reaction, and a slow reaction.
Fast reaction - burning / explosions
Slow reaction - rusting
When does a reaction stop?
When all the reactants are used up
Word equation for magnesium reacting with hydrochloric acid?
magnesium + hydrochloric acid → magnesium chloride + hydrogen
What does rate of reaction measure?
the amount of product formed in a fixed period of time.
• In a slow reaction, a small amount of product will form in
a long time.
• In a fast reaction, a large amount of product will form in
a short time.
How do you measure the volume of gas produced in a reaction?
Using a gas syringe
Word equation for calcium carbonate and hydrochloric acid?
calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide
What is a limiting reactant?
The reactant that is used up first
How can you tell the rate of reaction on a graph?
the gradient or slope of the line on a graph of amount of product against time.
What is the link between temperature and rate of reaction?
As the temperature increases, the rate of reaction increases, too. Increasing the temperature increases the chance of a successful collision (one that causes a reaction) because the particles have more energy. It also increases the collision frequency. Not only do the reactant particles collide more often, the collisions themselves have more energy and so are more likely to be successful.
Why does high pressure increase the rate of reaction?
When gases are put under pressure, their particles become more crowded. They do not gain energy, but they do have more frequent collisions.
What does rate of reaction depend on?
the amount of energy transferred during the collisions; and the frequency of collisions.
What is the concentration of a solution?
a measure of how much solute is dissolved in the solvent.
How does concentration affect rate of reaction?
If a reaction involves one or more reactants in solution, the rate of reaction increases as the concentration increases. When solutions are more concentrated, their particles become more crowded. They do not gain energy, but they do have more collisions.
What is an explosion?
a very fast reaction in which a large volume of hot gases is released in a short time. The expanding gases create a shock wave that travels at high speed, damaging objects in its path.
What is TNT? How does it work?
TNT is a high explosive. The shock waves that exploding TNT produces travel faster than the speed of sound, giving it the potential to cause a lot of damage. TNT is a yellow solid at room temperature. When it explodes, it produces solid carbon and a large volume of gases.
What is dynamite made of?
It consists of an explosive liquid, nitroglycerine, absorbed in a mineral powder. This makes it safer to handle than the liquid alone.
Why does using powder increase rate of reaction?
A powder has a larger surface area than a lump of the same mass. The larger the surface area, the greater the frequency of collisions and the faster the reaction.
What is a combustible substance? Examples? What does it do?
Combustible substances burn easily. Combustible powders such as flour, custard powder and sulfur burn explosively in air. This makes them very dangerous in factories where they are manufactured or used. Care must be taken to stop dust escaping into the air inside buildings, and to prevent sparks or naked flames.
What is a catalyst?
A substance which changes the rate of reaction but is unchanged at the end of the reaction.
Why are catalysts useful in the chemical industry?
Without them, many industrial processes would be too slow to be economical. For example, iron is used in the Haber process, which makes ammonia for fertilisers and explosives.
What is the difference between relative formula mass and chemical formula?
The chemical formula of a substance tells you the number of each type of atom in a unit of that substance. The relative formula mass or Mr of a substance is the mass of a unit of that substance compared to the mass of a carbon atom. It is worked out by adding together all the Ar values for the atoms in the formula.
What is conservation of mass?
the total mass is the same before and after the reaction.
Why is mass conserved?
because no atoms are created or destroyed in chemical reactions
