Chemistry

Question 1

What is a physical change?

Answer 1

A physical change is a change that occurs with no chemical reaction, including changes of state.

Question 2

What is chromatography used for?

Answer 2

Chromatography is used to separate components in a mixture by dissolving the sample in a solvent and dragging it through a medium. The components travel at different rates, causing them to separate.

Question 2

What is a chromatogram?

Answer 2

A chromatogram is the result or the medium where the components are separated in chromatography.

Question 3

What is a chemical change?

Answer 3

A chemical change involves a chemical reaction.

Question 3

What are the main changes of state in matter?

Answer 3

The main changes of state are: Melting (Solid to Liquid), Evaporation (Liquid to Gas)
Condensation (Gas to Liquid)
Solidification (Liquid to Solid)
Sublimation (Solid to Gas)
Deposition (Gas to Solid)

Question 4

What is solvent extraction?

Answer 4

Solvent extraction involves adding a solvent to dissolve one component of a mixture, such as dissolving salt from a sand and salt mixture using water.

Question 5

What is distillation?

Answer 5

Distillation is a technique where a mixture is heated to separate solute and solvent by evaporation and condensation, allowing the retention of both components.

Question 6

What is recrystallization?

Answer 6

Recrystallization is the process of evaporating a solvent to form crystals of a solute.

Question 7

What is gravity separation?

Answer 7

Gravity separation is a technique that separates substances based on their density, often used for suspensions or precipitates.

Question 8

What is hand separation?

Answer 8

Hand separation involves physically sorting components of a mechanical mixture, such as separating M&Ms by color or using magnets to separate magnetic materials like Fe, Ni, Co.

Question 9

What is filtration?

Answer 9

Filtration is the process of separating a solid from a liquid in a suspension by passing it through a filter. The solid is called the residue, and the liquid is the filtrate.

Question 10

What is evaporation (in separation techniques)?

Answer 10

Evaporation involves heating a mixture to remove the solvent, leaving the solid behind. This is useful for solutions where the solvent is not retained.

Question 11

What is matter?

Answer 11

Matter is anything that has mass and volume.

Question 12

What are the two main classifications of matter?

Answer 12

Pure Substances and Mixtures

Question 13

What are pure substances?

Answer 13

Pure substances consist of a single substance.

Question 14

What are the three types of mixtures?

Answer 14

Solutions – look like a uniform substance (e.g., salt water, apple juice, air).
Suspensions – separate into layers (e.g., salad dressing, milk).
Mechanical Mixtures – contain two or more visible substances (e.g., cereal, dirt, M&Ms).

Question 14

What are mixtures?

Answer 14

Mixtures contain two or more pure substances.

Question 15

What are the two types of pure substances?

Answer 15

Elements – cannot be broken down into smaller substances (e.g., Fe, O, Au).
Compounds – consist of two or more bonded elements (e.g., H₂O, NaCl).