Significant Digits, Measurements, and Estimations & Limiting Reactants

Question 1

Express an answer with…

Answer 1

the lowest sig figs.

Question 2

True or False?
1) Rule 1: all non-zero digits are insignificant.
2) Rule 2: Final zeroes to the right of the decimal point are insignificant.
3) Zeros between nonzero digits are significant.
4) Zeros to the left are significant.
5) ‘Exact’ numbers have infinite significant digits.

Answer 2

1) False.
2) False.
3) True.
4) False.
5) True.

Question 3

What is the general rule for measurement?

Answer 3

The last digit is an estimate called an uncertainty.

Question 4

How do we find the uncertainty?

Answer 4

You divide the small interval by half, then present the measurement with a +- value.

Question 5

What is the difference between accuracy and precision?

Answer 5

Accuracy is the closeness to the actual value. While precision is the closeness of repeated measurements to each other.

Question 6

How do you measure accuracy?

Answer 6

Percent error = (measured - expected) / expected x100

Question 7

What is a limiting reactant?

Answer 7

The reactant limits the extent of the reaction and determines the amount of product formed.

Question 8

What is an excess reactant?

Answer 8

The reactant(s) that is ‘leftover’ following a chemical reaction.

Question 9

What is the relationship in molar concentration? (C=n/v)

Answer 9

It tells us the amount of moles of a substance present in a particular volume of the solution.