Question

1. calculate the percent composition of a compound composed of sulfur and oxygen where the compound weighs 45.6 g, and contains 17.6 grams of sulfur.

a. 72.1% s, 27.8% o
b. 38.6% s, 61.4% o
c. 54.7% s, 23.3% o
d. 74.3% s, 24.0% o

1. how many liters are needed to prepare a 5m solution with 7.5 moles solute? (l = m x moles)

a. 1.5 l
b. 37.5 l
c. 2.5 l
d. 15 l

1. you are asked to prepare a 10 l solution of 5m nacl. how many grams of salt will you need? (moles = m x l)

a. 2920 g nacl
b. 0.855 g nacl
c. 116.88 g nacl
d. 0.5 g nacl

1. dilution: you are given 0.250 liters of 1.88 m hno3. you are asked to dilute the solution to a concentration of 0.125m. how many liters will the final solution be?

a. 0.47 l
b. 0.0588 l
c. 0.266 l
d. 3.76 l

1. convert the molecular formula of glucose (c6h12o6), to the empirical formula.

a. c12h24o12
b. c0.5ho0.5
c. c3h4o3
d. ch2o

1. molarity is a measure of:

a. volume
b. mass
c. density
d. concentration

1. calculate the percent composition of a compound that contains 15.7 g oxygen and 24.5 grams carbon. (2 points)

a. 64.1% o, 15.6% c
b. 39.1% o, 60.9% c
c. 15.3% o, 27.7% c
d. 56.1% o, 35.9% c

Explanation:

Step1: Calculate the mass of the compound

The mass of the compound is \(15.7 + 24.5=40.2\) grams.

Step2: Calculate the percent composition of oxygen

The formula for percent composition is \(\text{Percent Composition}=\frac{\text{Mass of Element}}{\text{Mass of Compound}}\times100\%\).
For oxygen: \(\frac{15.7}{40.2}\times100\% \approx 39.1\%\)

Step3: Calculate the percent composition of carbon

For carbon: \(\frac{24.5}{40.2}\times100\% \approx 60.9\%\)

Answer:

B. \(39.1\%\text{ O}, 60.9\%\text{ C}\)