Unit 10 Flashcards
What is rate
Rate is the measurement of how fast or slow something is
Rate is a measure of the Change that happens in a single unit of time
How to find the rate of a reaction
The amount of a reactant used up per unit of time
Or
The amount of a product produced per unit of time
What happens when you react magnesium and hydrochloric acid
It produces hydrogen gas
For a chemical reaction to occur…
The reactant particles must collide. But collisions with too little energy do not produce a reaction.
The particles must have energy for the collision to be successful in producing a reaction
The rate of reaction depends on the rate of successful collision between reactant and particles. The more successful collisions there are, the faster the rate of reaction
If the temperature is increased
The reactant particles move more quickly
They have more energy
The particles collide more often, and more of the collisions result in a reaction
The rate of reaction increases
If the concentration of a dissolved reactant is increased, or the pressure of a reacting gas is increased
The reactant particles become more crowded
There is a greater chance of the particles colliding
The rate of reaction increases
If a solid reactant is broken into smaller pieces of ground into a powder
It’s surface area increase
More particles are exposed to the other reactant
There are more collisions
The rate of reaction increases
What is a photo chemical reaction?
When some chemical reactions obtain energy from light.
Silver bromide is pale yellow. Why does it darken on exposure to light. Why
Because the light causes it to decompose to silver.
Equation for photosynthesis
Carbon dioxide + chlorophyll —> glucose + oxygen
What speeds up the photosynthesis reaction
The green substance chlorophyll (in leaves) that speeds up a reaction
The stronger the light, the more energy it provides so the faster the reaction goes
What is a catalyst
A substance that can increase the rate of a reaction. The catalyst itself remains unchanged at the end of the reaction is catalysed. Only a very small amount of catalyst is needed to increase the rate of reaction between large amounts of reactants
A catalyst works by lowering the activation energy for the reaction
What are enzymes
They are proteins that act as catalysts so they are often called biological catalysts
How enzymes work
First the enzyme and the reactant molecule fit together like jigsaw pieces. The reactant molecule has to be the right shape. The enzyme breaks down the molecule to smaller pieces and so on
Conditions in which an enzyme works the best in
An enzymes works best in conditions that match those in the living cells it came from
This means most enzymes work best in the temperature range 25-45 degrees celsius . If the temperature is too high, an enzyme loses its shape and it becomes denatured
An enzyme also works best in a particular pH range
