G9 Q2 S5 Percentage Composition

What is the general formula for the computation of percentage composition of the given element?

• % mass of element = mass of element in the compound divided by mass of the compound times 100

• % mass of element = mass of element in the compound divided by mass of the compound

• % mass of element = mass of element in the compound divided by 100

• % mass of element = mass of element in the compound

What is the percent by mass of magnesium in MgO?

• 20%

• 40%

• 50%

• 60%

What is the percent by mass of fluorine in CaF₂ (gram-formula mass = 78 g/mol)?

• 24%

• 49%

• 39%

• 65%

Which of the following is NOT needed to calculate percent composition?

• Mass of specific element

• Molar Mass

• Avogadro's Number

• Division

Find the percent composition of Cu₂S?

• %Cu= 67.987 %S= 32.013

• %Cu= 79.854 %S= 20.145

• %Cu= 35.946 %S= 64.054

How many percent of chlorine is present in chloroform?

• 10.06%

• 0.84%

• 89.09%

• 99.99%

Tags

NGSS.HS-PS1-7

The label of the dark chocolate indicates that its mass is 150g and it is 70%

cacao, if you consume the whole chocolate bar, how much cacao did you eat?

• A. 105 g cacao

• B. 45 g cacao

• C. 100 g cacao

• D. 50 g cacao

The presence of SO₂ in the atmosphere causes acid rain. How many percent of sulfur is present in SO₂ (S= 32.07, 0=16.00; Molar Mass = 64.07g/mole)?

• 40.00%

• 49.95%

• 60.00%

• 50.05%

Tags

NGSS.HS-PS1-7

In cold areas, many fish and insects, including the common housefly, produce large amounts of glycerol (C₃H₈O₃ Molar Mass = 92.11 g/mole) to lower the freezing point of their blood. How many percent of oxygen is present in glycerol?

(C= 12.01, H= 1.01, O=16.00)

• 52.11%

• 50.11%

• 51.11%

• 53.11%

It is the ratio of the mass of an element compared to the compound’s mass.

• Molar Mass

• Percentage Composition

• Molar Concept

• Molecular Mass