CHAPTER 1- Chemistry: The Study of Change
A. Kweyete
1. Classify the following as a pure substance (element (e)-compound (c)) or a mixture(m)
(homogeneous-heterogeneous).
a) air (homo-m)
b) a nickel (homo-m)
c) magnesium (e) d) sea water (homo-m)
d) gasoline(homo-m)
2. Perform the following conversions:
a) 0.0025 mm to nm => (0.0025mm)(1m/1000mm)(109 nm/1m) = 2500nm
b) 0.88 pm to cm => (0.88pm)(1m/ 1012 pm)(100cm/1m) = 8.8 x10-11 cm
c) 2.50x10-6 kg/L to mg/ ml
=> (2.50 x10-6kg/L)(1000g/1kg)(1000mg/1g)(1L/1000ml) = 2.5 x 10-3 mg/ml
3. A cubic piece of nickel metal measures 5.25 cm on each edge. If the density is 8.9 g/cm 3,
what is the mass of the cube? Mass = (5.25cm)3 x 8.9 g/cm3 = 1287.9 g = 1290g (3 sig.
fig)
4. Determine the number of significant figures in each of the following measured
quantities?
a) 0.000289 m (3) b) 3.50x108 g (3)
c) 202.040 cm (6)
d) 8.089 L (4)
5. Perform the following calculations and round off the answer to the proper significant
figures:
a) 1.25 m + 6.2 m – 8.01 m + 0.899 m = _0.3m__________
b) 78.8680 g/ (23.5ml + 10 ml) = 78.8680 / 34 = _2.3 g/ml_________
6. An automobile is able to travel 900. mi on 35.8 gal of gasoline, what is the gas mileage in
km/L?
=> (900. mi/35.8 gal)(1.61 km/1 mi)(1 gal/ 4qts)(1.06qts/1 L) = 10.7 km/ L
7. Neon has a low boiling point of approximately –246 oC. What is the boiling point in Kelvins
and oF? K = oC + 273 = -246 + 273 = 27 K
o
F = (9/5)(-246) + 32 = - 411 oF
8. Round off the following to three significant figures:
a) 134.89 m = 135 m
b) 80 g = 80.0 g
c) 1255 mL = 1.26 x 103 mL or 1260
mL
d) 1.2x10-5 mm = 1.20 x10-5 mm
9. A balance has a precision of +/- 0.001g. A sample weighs about 8 g on this balance. How
many significant figures should be reported for this measurement?
=> 8.000 g => 4 sig. fig.
10. The density of a metal is 9.80 g/ml. What is the mass of a sample of metal when dropped
in 28.9 ml water, the volume increases to 56.4 ml?
Mass = (56.4ml – 28.9ml)(9.80g/ml) = 2.70 x 102 g or 270g
11. Label each of the following as either a physical process (change) or a chemical process
(change).
a) The metal gets warmer physical
b) Explosion of nitroglycerin chemical
c) Corrosion of Iron metal chemical
d) Water condenses on the metal physical
12. Identify the following characteristics as physical properties or chemical properties.
a) Silver metal is white physical
b) Zinc has a density of 7.13g/ml at 25 0C physical
c) Silver is a lustrous metal physical
d) Zinc is a good conductor of electricity physical