Chapter E Essentials: Units, Measurement and Problem Solving

Vocabulary flashcards covering units, measurement, and problem-solving concepts from the lecture notes.

Chemistry

The study of the composition, properties, and transformations of matter; an experimental science relying on observation and measurement.

empirical knowledge

Knowledge gained from observation and experiment rather than theory alone.

scientific method

A systematic process of investigation using observation, experiment, and reasoning to understand natural phenomena.

measurement

A quantitative observation with a magnitude and a unit; includes accuracy, precision, and uncertainty.

base units

SI units used as the fundamental references for measurements (e.g., meter, kilogram, second, kelvin, mole).

derived units

Units formed by combining two or more base units (e.g., m^2, m^3, g/cm^3, L).

SI prefixes

Prefixes indicating magnitude: mega (10^6), kilo (10^3), deci (10^-1), centi (10^-2), milli (10^-3), micro (10^-6), nano (10^-9).

meter (m)

The SI base unit of length.

kilogram (kg)

The SI base unit of mass; 1 g = 0.001 kg.

gram (g)

A derived unit of mass equal to 10^-3 kg.

second (s)

SI base unit of time.

kelvin (K)

SI base unit of thermodynamic temperature.

Celsius (°C)

Temperature scale commonly used alongside Kelvin.

mole (mol)

SI base unit for the amount of substance.

Kelvin and Celsius relationship

To convert Celsius to Kelvin: K = °C + 273.15.

temperature change equality

A change of 1 °C corresponds to a change of 1 K; 1 °C change equals 1.8 °F.

area

Derived unit: square meter (m^2).

volume

Derived unit: cubic meter (m^3) or liter (L).

density

Derived quantity: mass per volume; commonly g/cm^3 or g/mL.

accuracy

Closeness of a measurement to the true value.

precision

Repeatability or reproducibility of a measurement.

scientific notation

Expressing numbers as a × 10^b to handle very large or small values.

uncertainty

The last digit of a measurement; indicates the measurement's estimation.

significant figures

Digits that carry meaning about the precision of a measurement.

leading zeros

Zeros at the beginning of a number; not significant, only place the decimal point.

interior zeros

Zeros between significant digits; always significant.

trailing zeros with decimal

Trailing zeros after a decimal point are significant.

trailing zeros without decimal

Trailing zeros without a decimal point may be ambiguous in significance.

exact numbers

Numbers known with certainty (counts, defined constants); have unlimited significant figures.

multiplication/division SF rule

The result has as many significant figures as the factor with the fewest SF.

addition/subtraction SF rule

The result has as many decimal places as the measurement with the fewest decimal places.

dimensional analysis

Using conversion factors to convert units and cancel undesired units.

conversion factor

An exact ratio used to convert units (e.g., 1000 g = 1 kg).

units must be like for addition/subtraction

Only like units can be added or subtracted.

canceling units

Arrange factors so unwanted units cancel in a calculation.

minutes to seconds

Convert minutes to seconds using 1 min = 60 s.

height to meters

Convert feet and inches to inches, then to centimeters, then to meters (1 ft = 12 in; 2.54 cm = 1 in; 1 m = 100 cm).

carpet cost example

Cost calculation using area and price per unit area; convert area to appropriate unit (e.g., yd^2) when given in another unit.

count vs exact numbers

Counts of discrete objects are exact numbers with unlimited SF (e.g., 146 students).

mL to dL conversion

There are 100 mL in 1 dL; 1.5 dL equals 150 mL.

volume units

Common volume units include m^3 and L.

decimal places and precision

Higher precision is indicated by more decimal places in a measurement.