Moles and Conversions

Which of the following methods should be used in order to calculate the molar mass of magnesium hydroxide?

• Add the masses of two moles Mg to the mass of one mole OH

• Add the total protons and neutrons.

• Add the masses of one mole Mg to the mass of one mole OH

• Add the masses of one mole Mg to the masses of two moles of OH.

A student calculated the number of moles of methane (CH4) present in a 100g sample of a gaseous mixture. If the student determined that there’s 0.6 moles of methane present in the sample, what is the percent composition of methane in the sample?

• .096%

• 9.6%

• .9%

• 90%

When converting a mass to moles, what unit must be in the denominator of the conversion factor?

• grams

• moles

• grams/mole

Convert 50.0 grams of H₂O to moles of H₂O.

• 901 moles

• 18.02 moles

• 2.77 moles

What mass of calcium chlorate, Ca(ClO₃)₂, is equivalent to 0.750 moles of the substance?

• 155.24 grams

• 206.98 grams

• 128.65 grams

2.50 moles of sodium sulfate, Na₂SO₄, are added to a solution. What mass of the substance was this?

• 297.65 grams

• 142.05 grams

• 355.13 grams

Tags

NGSS.HS-PS1-7

What is the molar mass of aluminum carbonate, Al₂(CO₃)₃?

• 54.99 g/mol

• 233.99 g/mol

• 185.99 g/mol

3.0 moles of sodium hydroxide, NaOH, is equal to what mass?

• about 40 grams

• about 23 grams

• about 120 grams

176 grams of carbon dioxide, CO₂, is equal to how many moles of the substance.

• about 44 moles

• about 4 moles

• about 1 mole

When converting a moles to mass, what unit must be in the denominator of the conversion factor?

• grams

• moles

• grams/mole