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Dimensional Analysis quiz

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  • What is the main purpose of dimensional analysis in chemistry?
    Dimensional analysis is used to convert from one unit to another by systematically canceling out unwanted units using conversion factors.
  • What is a conversion factor in dimensional analysis?
    A conversion factor is a ratio that relates two different units and is used to convert between them.
  • How do you set up a conversion factor to cancel out unwanted units?
    Place the unwanted unit in the denominator of the conversion factor so it cancels with the same unit in the numerator of the given amount.
  • If you are converting inches to centimeters, what conversion factor should you use?
    You should use the conversion factor 1 inch = 2.54 centimeters.
  • When multiplying numbers in dimensional analysis, how do you determine the number of significant figures in the final answer?
    The final answer should have the same number of significant figures as the value with the least number of significant figures in the given data.
  • Why is it important to line up units on opposite levels in dimensional analysis?
    Lining up units on opposite levels ensures that unwanted units cancel out, leaving only the desired unit.
  • In a multi-step conversion (e.g., minutes to years), what must you do at each step?
    At each step, use a conversion factor to cancel out the current unit and introduce the next unit until you reach the desired end unit.
  • When converting 32 inches to centimeters, why is the answer rounded to 2 significant figures?
    Because the given value (32 inches) has 2 significant figures, so the answer must also have 2 significant figures.
  • What is the general strategy for solving dimensional analysis problems?
    Start with the given amount, use conversion factors to cancel unwanted units, and continue until you isolate the desired end unit.
  • When converting 115 minutes to years, which value determines the number of significant figures in the final answer?
    The number of significant figures in the final answer is determined by the given value (115 minutes), not the conversion factors.
  • Why are conversion factors not used to determine significant figures in the final answer?
    Because conversion factors are considered exact values, so only the given measured values determine significant figures.
  • What is the result of converting 115 minutes to years using dimensional analysis?
    The result is 2.19 × 10⁻⁴ years, rounded to 3 significant figures.
  • What should you do when you have multiple numbers to multiply in the denominator during dimensional analysis?
    Multiply all the numbers in the denominator together first to simplify the calculation.
  • What is the ultimate goal of dimensional analysis?
    The goal is to systematically cancel out all units except for the one you want in your final answer.
  • How do you count significant figures in a number without a decimal point?
    Start counting from the right at the first nonzero digit and count all digits to the left.