Chemistry Rates of Reaction and Conservation of Mass

Practice flashcards to review key concepts related to rates of reaction and the law of conservation of mass in chemistry.

What do "big numbers" in front of formulae indicate?

They tell us how many units of each formula there is in the balanced equation.

What do "small numbers" in formulae represent?

They indicate how many atoms of each kind are in a formula.

What is the law of conservation of mass?

Atoms are not created or destroyed in a chemical reaction.

Why does the mass decrease in the reaction of metal + acid?

Atoms are being lost as a gas, specifically hydrogen.

Why does the mass increase in the reaction of magnesium + oxygen?

Atoms from a gas (oxygen) are being added.

What is the unit and symbol for mass?

Kilogram (kg) or gram (g).

What is the unit and symbol for volume?

Cubic metres (m³), cubic centimetres (cm³), or cubic decimetres (dm³).

What is concentration?

The amount of solute dissolved per unit volume of solvent.

What is the unit and symbol for concentration (when using mass)?

Grams per cubic decimetre (g/dm³).

What must particles do in order to have a chance to react?

They must collide with sufficient energy and in the correct orientation.

What is rate of reaction?

How quickly a reaction takes place.

What are the units and symbols for rate of reaction?

Cubic centimetres per second (cm³/s) or grams per second (g/s).

How can you monitor rate of reaction?

By measuring the volume of gas produced per second using a gas syringe or measuring changes in concentration.

What is turbidity?

Cloudiness or changes in clarity of a solution.

How can you calculate relative rate from time taken?

Relative rate = 1/time taken.

On a graph of concentration/mass/volume of gas against time, what is represented by the gradient?

The rate of reaction.

What are the 5 factors that can alter the rate of reaction?

Temperature, surface area, pressure (gases), concentration, and catalysts.

How does temperature affect the rate of reaction?

Increasing temperature increases the rate of reaction.

What needs to happen to collisions between particles to increase rate?

Increased frequency and/or increased energy.

How do particles behave at higher temperatures?

They move faster and collide more frequently.

What do particles have more of at higher temperatures?

More energy.

Which state of matter can we alter the pressure of?

Gases.

How does pressure affect the rate of reaction?

Increasing pressure increases the rate of reaction.

How are particles spaced at high pressure?

Closer together, resulting in more particles per unit volume.

How does concentration affect the rate of reaction?

Increasing concentration increases the rate of reaction.

How are particles spaced at low concentration?

Further apart, resulting in fewer particles per unit volume.

What effect does breaking solid matter into smaller bits have on surface area?

Increases surface area to volume ratio.

How does surface area affect the rate of reaction?

Increasing surface area increases the rate of reaction.

Why does a larger surface area increase the rate of reaction?

More particles are at the surface and available for collisions.

What is activation energy?

The minimum energy with which particles must collide in order to react.