Lesson Worksheet: Percentage Composition Chemistry • 10th Grade
In this worksheet, we will practice calculating the percentage composition of a substance using chemical formulas or the masses of constituent elements.
Q1:
A 5.0 g sample of spinal fluid contains 3.75 mg (0.00375 g) of glucose. What is the percent by mass of glucose in spinal fluid?
Q2:
A bottle of a tile cleanser contains 135 g of and 775 g of water. What is the percent by mass of in this cleanser?
Q3:
A compound contains only the elements X and Y. A sample of the compound with a mass of 12.5 g is found to contain 6.50 g of X. What is the percentage composition of the compound?
- A,
- B,
- C,
- D,
- E,
Q4:
A 10 g sample of silicon carbide is found to contain 3.0 g of carbon. What is the percentage composition of silicon carbide?
- A,
- B,
- C,
- D,
- E,
Q5:
What is the percentage composition of calcium carbonate ? State percentages to 1 decimal place. [, , ]
- A, ,
- B, ,
- C, ,
- D, ,
- E, ,
Q6:
To 1 decimal place, calculate the oxygen content of a water molecule as a percentage of the total mass. [, ]
Q7:
A compound contains a known mass of element . What is the formula for expressing the mass of in compound as a percentage of the total mass?
- A =
- B =
- C =
- D =
- E =
Q8:
A compound Y contains one atom of element X per formula unit. The relative formula mass of Y is known. What is the formula for expressing the mass of X in compound Y as a percentage of the total mass?
- A =
- B =
- C =
- D =
- E =
Q9:
A sample of a compound composed of only elements and has a mass of 50 g. After elemental analysis, it is shown that the sample contains 45 g of . To the nearest percentage unit, what is the mass of in the sample as a percentage of the total mass?
Q10:
A sample of a compound has a mass of 80 g and is composed entirely of elements and . Elemental analysis shows that the sample contains 20 g of . To the nearest percentage point, what is the mass of in the sample as a percentage of the total mass?