Question

module 0: intro. to chemistry and measurement

1. how many significant digits are in the value 0.0020340?
2. how many significant digits are in the value 230,005,000?
3. perform the following operations. make sure that your answers have been rounded to the correct number of significant digits.

a. 4.15 cm × 1.8 cm
b. 13.00 m − 0.54 m
c. (1.7 × 10⁻⁹ m) × (3.72 × 10⁻⁴ m)

1. what are the values of the following prefixes?

a. kilo-
b. hecto-
c. deca-
d. base unit
e. deci-
f. centi-
g. milli-

1. convert 600 mg to kilograms.
2. convert 250 g to milligrams.
3. what is the density of an object with a mass of 26.4 g and a volume 13.20 ml?
4. what is the mass of an object with a density of 0.356 g/ml and volume of 125 ml?
5. a graduated cylinder contains 10.0 ml of water. a sample of 10.0 g of an unknown metal is dropped into the cylinder, raising the level of water in it to 60.0 ml. what is the density of the metal sample?

use dimensional analysis to solve the following problems:

1. calculate the number of seconds in 40.0 hours.
2. what is the equivalent of 0.35 lb. in grams? (hint: 1 kg = 2.2 lb.)

Explanation:

Step1: Count non-leading zero sig figs

0.0020340 has digits 2,0,3,4,0 (leading zeros ignored)

Step2: Confirm significant digits

All 5 digits are significant (trailing zero after decimal counts)

Step1: Identify non-placeholding digits

230,005,000 has digits 2,3,0,0,0,5 (trailing zeros are placeholders)

Step2: Count significant digits

The 6 non-placeholder digits are significant

Step1: Calculate product

$4.15 \times 1.8 = 7.47$

Step2: Round to 2 sig figs

Least precise value (1.8) has 2 sig figs, so $7.47 \approx 7.5$

Step1: Calculate difference

$13.00 - 0.54 = 12.46$

Step2: Round to 2 decimal places

13.00 has 2 decimal places, so $12.46$ stays

Answer:

5

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