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General Chemistry: Chemistry and Measurements

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Termini in questo insieme (22)

  • What is matter?

    Matter is anything that has mass and volume.

  • Define a chemical.

    A chemical is a substance that always has the same composition and properties wherever found.

  • List the steps of the scientific method.

    1. Observation
    2. Hypothesis
    3. Experiment
    4. Model (Theory)
    5. Further Experiment

  • Difference between qualitative and quantitative analysis.

    Qualitative analysis studies properties like color, smell, texture.
    Quantitative analysis involves measurements like mass, length, volume, temperature.

  • What are SI units?

    SI units are the revised metric system accepted worldwide, consisting of seven base units and many derived units.

  • Name the seven SI base units.

    Mass: kilogram (kg)
    Length: meter (m)
    Time: second (s)
    Temperature: Kelvin (K)
    Amount of substance: mole (mol)
    Electric current: ampere (A)
    Luminous intensity: candela (cd)

  • Examples of SI derived units.

    Area: square meter (m\(2\))
    Volume: cubic meter (m\(3\))
    Density: kg/m\(3\)
    Velocity: m/s

  • What is scientific (exponential) notation?

    A way to express very large or very small numbers as a decimal part times 10 raised to an exponent, e.g., 1.2345 × 10\(4\).

  • Rules for the decimal part in scientific notation.

    The decimal part must be ≥ 1 and < 10; the exponent is adjusted accordingly.

  • What are decimal prefixes? Give examples.

    Prefixes to simplify large or small numbers, e.g., kilo (k) = 10\(3\), milli (m) = 10\(-3\), micro (μ) = 10\(-6\).

  • How to determine significant figures in a measurement?

    Significant figures include all certain digits plus one estimated digit; leading zeros are not significant, trailing zeros right of decimal are significant.

  • Rules for trailing zeros and significant figures.

    Trailing zeros left of decimal with a decimal point count as significant; without decimal point, they do not.

  • How to handle significant figures in addition and subtraction?

    The result should be rounded to the least number of decimal places of any number in the operation.

  • How to handle significant figures in multiplication and division?

    The result should have the same number of significant figures as the number with the fewest significant figures.

  • What is dimensional analysis?

    A method to convert units by multiplying by conversion factors that cancel units systematically.

  • How to convert units using conversion factors?

    Multiply the quantity by a fraction equal to one, where numerator and denominator are equivalent quantities in different units.

  • Example: Convert 24 eggs to dozens.

    24 eggs × (1 dozen / 12 eggs) = 2 dozen

  • How to convert derived units like volume?

    Cube the conversion factor for length units, e.g., 1 m = 3.28 ft implies 1 m\(3\) = 35.3 ft\(3\).

  • Define density and give its formula.

    Density is mass divided by volume: \(d=\frac{m}{V}\).

  • Why does mineral oil float on water?

    Because mineral oil has a lower density than water, it floats on top in a gravitational field.

  • What is specific gravity?

    Specific gravity is the ratio of the density of a sample to the density of water; it is dimensionless.

  • How to calculate percent, ppm, and ppb?

    Percent = (part/whole) × 100
    ppm = (part/whole) × 10\(6\)
    ppb = (part/whole) × 10\(9\)