Chemistry 2.3 Review

​ (a)   is how close your measurement is to the "accepted" value, while ​ (b)   is how close your measurements are to each other.

• Accuracy
• Precision
• Correctness
• Error

How precisely a tool is able to make a measurement is based on its what?

• Error

• Percent Error

• Significant Figures

Answer explanation

While error and percent error are indeed ways to see how precise a measurement is, the number of significant figures a tool is able to give you tells you how precise the tool itself is. Error and percent error could be based on operator error.

Match the following numbers to their significant figures AND the reasoning for how many they have.

• 404 grams

• Infinite, because it's a counting number

• 34.0 grams

• 3 sig figs, because zeroes after a decimal AND a significant number are significant

• 257 grams

• 3 sig figs, because non-zero numbers are always significant

• 220 grams

• 2 sig figs, the 0 is trailing and is not significant

• 10 apples

• 3 sig figs, the zero between non-zero numbers is always significant

Round the number 25,470 to the hundreds place.

Mathematical Equivalence

ON

Round the number 125.25 to the tenths place

Mathematical Equivalence

ON

When adding and subtracting numbers, you should round your answer to ​ (a)   .

When multiplying and dividing numbers, you should round your answer to ​ (b)   .

• the smallest shared decimal place
• the least number of sig figs involved
• two decimal places