Chapter 2 - Volume, Mass, Density, Conversions, and Temperature

2.1 - Measurement

  • SI Prefixes: names, symbols, and meanings

  • Common Metric Prefixes

    • Kilo - k - 1,000 of the base

    • Deci - d - 1/10

    • Centi - c - 1/100

    • Milli - m - 1/1,000

    • Micro - µ - 1/1,000,000

    • See notebook for equations we will have to memorize

  • English to Metric Conversions - Will be given to us on the test

  • Accuracy - closest to the correct measurement

  • Precision - how close the values are to one another

    • accuracy vs. precision photo example

  • Exact Measurements - are values for which there is NO uncertainty

    • exactly 7 pennies is an example of exact measurements

    • 1 mg = 0.001 g and 3 feet = 1 yard

  • Estimated measurements - where you have to make an estimate, or a guess, as to what the number is.

    • this often happens when you read from a scale

    • Estimate the temperature reading from thermometer A:

      • 21.6 degrees - 21 is certain and the .6 is estimated/ uncertain digit: there are 3 significant figures.

    • the uncertain digit is always the last digit

    • if there are 0s to the left of the numbers they are not significant numbers, but zeros to the right will be significant in a number with a decimal

  • Multiplication or Division: The Rule is:

    • the number of significant figures in the result should be equal to the original number that has the smallest number of significant figures.

    • See notebook for examples

  • Addition and subtraction the rule is

    • the answer will have its certain, or last digit in the same place as the measurement with the uncertain difit furthest to the left

2.2 Conversions

  • How many meters in 34.5?

  • Ans 3.45 × 10^-5 m

  • 2.2 dimensional in notebook examples

  • Volume: liters are commonly used unit for volume

    • box example - V = L x W x H

    • 1 cm x 1cm x 1cm = 1cm³ = 1mL (remember)

2.3 Density

  • Density is not the same as mass!!

  • Mass - is a measure of how much matter an object has

  • Density is a measure of the matters concentration: therefore, to calculate the density of an object, you have to make the mass of an object and divide by its volume.

    • See notebook for formula to MEMORIZE

  • Units for density are always some mass/ volume:

  • But they may be g/L , kg/m³, or other appropriate units depending on the context and materials being measured.

  • Algebraic Manipulation:

    • take equation d=m/V, solve for m and V:

      • See notebook

  • Calculate the volume of a sample of aluminum

    (density of aluminum is 2.13 g/mL) if you have 30.0

    g sample.

    • 30g = mass

    • Volume = ?

    • 2.13 g/mL = Density

  • Density Demo coke cans in water- lesser density floats, greater density sinks

    • diet coke is less dense than classic coke, this is because of the dissolved sugar

2.4 temperature scales

  • Kelvin is the SI unit of temperature

  • the side of a “degree“ on the Kelvin scale is the same as on the Celsius scale

    • zero on the celsius scale is water freezing temp

    • Zero on Kelvin is when all molecules stop moving

    • K = C + 273.15 ——> This will be given on the test

  • The side of a “degree” on the Fahrenheit scale is not the same as celsius scale

    • F= 1.8 x C + 32 ——> This will be given on the test

  • What is “absolute zero”?

    • notebook

    • the point where all molecules stop moving completely