Mole Conversions and Molar Mass

The video tutorial covers two-step mole conversions, focusing on two problems. The first problem involves calculating the number of molecules in a 32.5-gram sample of water, using moles as a conversion factor. The second problem reverses the process, finding the mass of titanium chloride from a given number of formula units. The tutorial emphasizes the role of moles as a middleman unit between the number of objects and mass, and demonstrates the use of molar mass and Avogadro's number in these calculations.

What is the role of moles in two-step mole conversions?

• Moles are used to measure temperature.

• Moles act as a middleman unit between count and mass.

• Moles are used to measure volume.

• Moles are used to measure pressure.

What is the first step in solving for the number of molecules in a given mass of water?

• Convert grams to moles using molar mass.

• Convert grams to kilograms.

• Convert grams to liters.

• Convert grams to atoms.

What is the molar mass of water (H2O)?

• 16 grams per mole

• 18 grams per mole

• 20 grams per mole

• 22 grams per mole

How many molecules are in one mole?

• 3.02 x 10^23

• 6.02 x 10^23

• 9.02 x 10^23

• 12.02 x 10^23

What is the final step in calculating the number of molecules in a water sample?

• Divide by the number of moles.

• Multiply by Avogadro's number.

• Subtract the molar mass.

• Add the number of moles.

What is the first step in converting from formula units to mass?

• Convert formula units to kilograms.

• Convert formula units to atoms.

• Convert formula units to moles using Avogadro's number.

• Convert formula units to liters.

What is the formula of titanium(II) chloride?

• TiCl

• TiCl2

• TiCl3

• TiCl4

What is the molar mass of titanium(II) chloride?

• 100 grams per mole

• 128 grams per mole

• 110 grams per mole

• 118 grams per mole

How do you calculate the mass of a sample from the number of formula units?

• Multiply by the molar mass and divide by Avogadro's number.

• Divide by the molar mass and multiply by Avogadro's number.

• Subtract the molar mass from Avogadro's number.

• Add the molar mass and Avogadro's number.

What is the mass of 3.0 x 10^21 formula units of titanium(II) chloride?

• 0.29 grams

• 0.59 grams

• 0.39 grams

• 0.49 grams