Miscellaneous

Question 1

State the Conservation of Mass in a reaction. (1)

Answer 1

The Conservation of Mass states that no atoms are created or destroyed in a chemical reaction. The total mass of the products in a chemical reaction will be the same as the total mass of the reactants. (1)

Question 2

Write word equations for combustion and incomplete
combustion. (2)

Answer 2

Complete combustion reaction is:
Fuel + O2 → CO2 + H2O. (1)

Incomplete combustion is:
Fuel + O → CO + C + H2O. (1)

Question 3

Label the Bunsen burner and how to light and use it
safely. (7)

Answer 3

1. Make sure there are no breaks or holes in the gas hose.
2. Ensure lab rules.
3. Put the Bunsen burner on a heat-resistant mat, making sure it isn’t near the edge of the bench.
4. Turn the collar to ensure the air hole of the Bunsen burner is closed.
5. Hold a lit splint 1-2 cm above the top of the barrel of the burner.
6. Turn on the gas at the gas tap, and the Bunsen burner will burn with a yellow flame.
7. Extinguish the splint and place it on the heat-resistant mat. (7)

Use BBC BITESIZE for image (2)

Question 4

Distinguish between a control, independent and dependent variable. (3)

Answer 4

Independent variables – the variable that is being changed during the experiment. (1)

Dependent variables – the variable being tested or measured during the experiment. (1)

Control variables - the variable that you do not change during an experiment. (1)

Question 5

Draw and label the most common apparatus used in
chemistry

Answer 5

Beaker:

A cylindrical container with a flat bottom and a lip for pouring. It is used for mixing, stirring, and heating liquids.
Flask (Erlenmeyer Flask):

A conical-shaped container with a narrow neck. It is used for titration, mixing, and holding liquids.
Test Tube:

A small cylindrical tube with an open top. Used for holding, mixing, and heating small quantities of liquids.
Burette:

A long, graduated tube with a stopcock at the bottom. It is used for delivering precise volumes of liquid in titrations.
Pipette:

A slender tube used to transfer small amounts of liquid. There are different types, such as volumetric pipettes and micropipettes.
Graduated Cylinder:

A tall, narrow cylinder with calibrated markings for measuring volumes of liquids.
Funnel:

A cone-shaped device with a narrow neck, used to channel liquids into containers with smaller openings.
Evaporating Dish:

A shallow, flat-bottomed dish used for evaporating liquids to leave behind solutes.
Watch Glass:

A circular, flat glass dish with a slight lip. It is used as a cover for beakers or evaporating dishes and for holding small amounts of substances.
Crucible and Cover:

A small, heat-resistant container with a lid used for heating substances to high temperatures.
Mortar and Pestle:

A pair of tools used to grind and mix substances into a fine powder.
Bunsen Burner:

A gas burner used for heating, sterilization, and combustion reactions in the laboratory.
Thermometer:

An instrument used to measure temperature.
Retort Stand and Clamp:

A support structure with a clamp used to hold glassware and other apparatus securely.
Centrifuge:

A machine used to separate components of a liquid mixture based on their densities, typically used in biochemistry and molecular biology.
These are just a few examples of the many apparatus used in chemistry laboratories. Each piece serves a specific purpose in carrying out experiments, measurements, and analyses.