CHEM MATH REVIEW

Accuracy and Precision

100

Measurements that are close to the accepted or true value demonstrate this quality.

What is accurate?

200

Measurements that are close to each other demonstrate this quality.

Answer: What is precision?

300

A thermometer consistently reads 6.0°C higher than the actual temperature. Is it accurate or precise?

What is precise?

400

Student A's measurements are clustered closely together but far from the accepted value. These measurements have high ________ but low ________.

What is precision; accuracy?

500

Two students measure an object with an accepted value of 10.0 cm. Student A gets 9.9, 10.0, 10.1 cm, while Student B gets 8.5, 8.6, 8.5 cm. Identify which student is more accurate and which is more precise.

 What is Student A is more accurate, and Student B is more precise?

Percent Error

100

Write the formula for percent error.

Percent Error=∣Experimental Value−Accepted Value∣/accepted value×100

200

 A student measures the density of a liquid as 0.95 g/mL; the accepted value is 1.00 g/mL. Calculate the percent erro

What is 5%?

300

A titration yields an experimental concentration of 0.124 M while the true is 0.120 M. Calculate percent error .

What is 3.33%?

400

 If percent error is reported as 0% in a student’s lab report, list two possible explanations

• The experimental value exactly matched the accepted/true value, resulting in 0% error.

• The values were rounded, making the experimental and accepted values appear equal even though a small difference may actually exist.

500

A measured value is 2.50 × 10^3 mol but the accepted value is 2.75 × 10^3 mol. Calculate the percent error

What is 9.09%?

Significant Figures

100

How many significant figures are in 0.005060? 

What is 4?

200

How many significant figures are in 3.040 × 10⁵?

What is 4 significant figures?

300

How many significant figures are in 700.0?

What is 4 significant figures?

400

alculate and report the answer using the correct significant figure rule:

12.34+5.6 

What is 17.9?

500

Calculate and report the answer using the correct number of significant figures:

4.56×2.1 

What is 9.6?

Scientific Notation

100

 Express 0.000456 in scientific notation.

What is 4.56×10^-4?

200

Express 0.00000000073 in scientific notation  

What is 7.3*10^-10

300

3.2 × 10^4  in standard form

What is 32,000?

400

Convert (3.2 × 10^4) × (4.5 × 10^-3) and give the result in correct scientific notation.

What is 1.4*10^2

500

 Divide (9.00 × 10^-5) by (3.0 × 10^2). Give the answer in scientific notation and proper significant figures.

What is 3.0*10^-7?