Chapter 1 Vocab: Chemical Foundations

Test taken 10/3

Significant figures

Numbers that express precision in measurement, indicating which digits are reliable and which are not.

when multiplying sig figs where do you look?

You look at the number with the least amount of significant figures to determine the number of significant figures in the result.

When dividing sig figs where do you look?

You look at the number with the least amount of signifcant figures and use that to determine the number of significant figures in your sum.

Where do you look when adding sig figs?

You look at the decimal place of the number with the least precise decimal to determine the number of decimal places in the result.

Law of conservation of mass

Matter cannot be created or destroyed, but it can be recycled into different forms. The mass of the ingredients before/after the reaction should be equal.

What is the difficult part about proving the Law of Conservation of mass using an experiment? How can it be proved?

During experiments the mass before and after WILL ALMOST ALWAYS be different because some of the matter usually falls out or escapes in the form of a gas.

SO, the experiments should be performed in a closed system.

What are properties of a chem

Where do you look when subtracting sig figs?

You look at the decimal place of the number with the least precise decimal to determine the number of decimal places in the result.

Property

What a substance is/does(Ex:flammability)

Change

what HAPPENS to a substance(Ex:burning=chemical change)

Physical

Same substance(melting,boiling,dissolving, crushing, cutting)

Chemical=NEW substance

burning, rusting, reacting, decomposing

how to do metric conversions

Copper reacting with nitric acid is a. . .

chemical change

A student claims:

“If something contains multiple elements, it must be a mixture.”

Is the student correct?

No. The student is not correct because a compound can contain multiple elements and it is not always a mixture.

For example- water is a compound and it contains two different elements(hydrogen and oxygen)

what is a mixture?

A term to describe two substances that are physically combined.

There are two different types: heterogenous(trail mix) and homogenous(salt water)

what is a compound?

different elements chemically bonded