Measurements in Chemistry

Question 1

I. Measurements

Answer 1

A. Measurements are quantities determined using an instrument.

Question 2

mass

Answer 2

resistance to being accelerated by an applied force (think how heavy)

Question 3

volume

Answer 3

space occupied by an object

Question 4

time

Answer 4

indefinite progression of events and existence

Question 5

distance

Answer 5

how far apart two objects are

Question 6

temperature

Answer 6

a measure of average kinetic energy (the energy of motion)

Question 7

Units: UNITS ALWAYS COUNT IN THIS CLASS!!!

Answer 7

Scientists typically use the metric system or the international system (SI) of units. You must be able to recognize
the type of measurement given either a metric or SI unit. (English provided only for reference).

Measurement Metric SI
Length Meter (m) Meter (m)
Volume Liter (L) cubic meter (m3)
Mass Gram (g) Kilogram (kg)
Temperature Celsius (°C) Kelvin (K)
Time* Seconds (s) Seconds (s)
*Minutes (min) and Hours (h) are also acceptable for time in all systems.

 Energy is not included in the table because it is not directly measured using an instrument, but you should
know its metric unit Joule (J) and English unit is calorie (cal, with lowercase C).

1 Food Calorie = 1 Calorie (Cal, uppercase C) = 1000 cal (lowercase C) = 1 kcal

Question 8

Metric Prefixes

Answer 8

precede the base unit to indicate a multiple or fraction of 10.

 They are used to conveniently express very large or small quantities.

Common prefixes to memorize at this point:
kilo k 1 kilo unit = 1000 units (or 1 ×103)
centi c 100 centi units = 1 unit (or 1 ×10−2)
milli m 1000 milli units = 1 unit (or 1 ×10−3)
micro μ 1 micro unit = 1 × 10−6 units
nano n 1 nano unit = 1 × 10−9 units

> It takes more of the smaller unit to equal one of the larger unit.

Ex: 2 km = two kilometers = 2 × 1000 m = 2000 m (two thousand meters)
Ex: 7 μg = seven micrograms = 0.000007 g = 7 × 10(to -6th power) g (seven times ten to the negative six power grams)

 Metric Prefixes must precede a base unit.

Ex: 10 m is ten ______________ (a unit of distance), while 10 mg is ten __________________ (a unit of mass).

Question 9

Scientific Notation

Answer 9

Another way to express a quantity in a condensed format.

Question 10

3 Parts to Scientific Notation:

Answer 10

i) a coefficient (rewrite number so the first non-zero digit is before the decimal point)
ii) a power of 10
o Numeral of power is how many places decimal was moved to write the coefficient.
o Exponent is positive if quantity was greater than one and negative if quantity was less than one.
iii) Retain the starting UNITS!

Ex 1: Express 2400 °C in scientific notation.
2400 °C

Ex 2: Express 0.0000083 m in scientific notation.
0.0000083 m

Question 11

Interpreting Scientific Notation

Answer 11

 more positive exponent = less negative exponent = larger quantity
 more negative exponent = less positive exponent = smaller quantity

Ex 3: Sort the following masses from smallest to largest. SMALLEST FIRST!
1 × 10(4th power) g 2 × 10(3rd power) g 4 × 10(2nd power) g 7 × 10(6th power) g