Question

1. in a lab, the melting point of salicylic acid is measured to be 45.87 degrees celsius. a chemistry handbook states the melting point to be 46.5 degrees. what is the percent error?
2. what is the percentage error of a mass measurement of 6.984 grams if the correct value is 6.699 grams?

rules for determining the number of significant figures.
determine if each of the following statements is true or false. write the word “true” or “false” in each

1. all nonzero digits in a measurement are significant.
2. zeros between nonzero digits are never significant.
3. in numbers less than 1, zeros to the left of the decimal serve as placeholders and are always significant.
4. in numbers less than 1, zeros to the immediate right of the decimal serve as placeholders and are never significant.
5. zeros to the right of a decimal and to the right of a nonzero number are significant.

indicate the correct number of significant figures in each of the following:

1. 0.032 m
2. 15.20 kg
3. 0.305 g
4. 3.500 km

30..00000007 m

1. 4500 liters
2. 26.42 cm³
3. 1056 dg
4. 60.0 cm

35..0047 ml

1. 1.60 mol

round each of the following measurements to the number of significant figures sho
37 314 721 meters (4 significant figures)

Explanation:

Step1: Recall percent - error formula

The percent - error formula is $\text{Percent Error}=\frac{\vert\text{Experimental Value}-\text{True Value}\vert}{\text{True Value}}\times100\%$.

Step2: Solve problem 19

The experimental value of the melting - point of salicylic acid is $45.87^{\circ}C$ and the true value is $46.5^{\circ}C$.
\[

$$\begin{align*} \text{Percent Error}&=\frac{\vert45.87 - 46.5\vert}{46.5}\times100\%\\ &=\frac{\vert- 0.63\vert}{46.5}\times100\%\\ &=\frac{0.63}{46.5}\times100\%\\ &\approx0.01355\times100\%\\ & = 1.36\% \end{align*}$$

\]

Step3: Solve problem 20

The experimental value of the mass is $6.984$ grams and the true value is $6.699$ grams.
\[

$$\begin{align*} \text{Percent Error}&=\frac{\vert6.984 - 6.699\vert}{6.699}\times100\%\\ &=\frac{\vert0.285\vert}{6.699}\times100\%\\ &=\frac{0.285}{6.699}\times100\%\\ &\approx0.04254\times100\%\\ &=4.25\% \end{align*}$$

\]

Answer:

1. $1.36\%$
2. $4.25\%$