Conversions using density or molar mass or both!

Which property would you use to convert from grams to moles?

• molar mass

• density

Answer explanation

To convert grams to moles, you use molar mass, which is the mass of one mole of a substance. Density relates mass and volume, but it does not directly convert grams to moles.

Which property would you use to convert from milliliters to grams?

• Density

• Molar mass

• volume

Answer explanation

To convert from milliliters to grams, you use density, which relates mass to volume. The formula is mass = volume × density, allowing you to find grams when you know the volume in milliliters and the substance's density.

Which property would you use to convert from moles to milliliters?

• Molar mass

• Density

• BOTH!!

Answer explanation

To convert moles to milliliters, you can use molar mass to find grams and then density to convert grams to milliliters. Therefore, BOTH properties are needed for the conversion.

Which of these is the correct dimensional analysis setup for the following question?

What is the mass of 3.74 moles of copper?

• none of these...you need density.

Answer explanation

The correct setup is \(\frac{3.74\ mol\ \times\ 63.55\ g}{1\ mol}\) because it converts moles of copper to grams using its molar mass (63.55 g/mol). This choice correctly applies dimensional analysis.

Which of these is the correct dimensional analysis setup for the following question?

What is the volume, in mL, of 59.3 cm³ of gold? Gold's density is 19.3 g/cm³.

Answer explanation

The correct choice is \(\frac{59.3\ cm^{3\ }}{ }x\ \frac{19.3\ g}{cm^3}\) because it sets up the relationship between volume and density, allowing us to find the mass of gold from its volume.

How many moles are in 50.0 grams of Aluminum? The density of Al is 2.70 g/cm³ and the molar mass is 26.98 g/mol.

• 1349 moles

• 1.85 moles

• 18.5 moles

How many grams are in a 500.0 cm³ block of Aluminum?

The density of Al is 2.70 g/cm³ and the molar mass is 26.98 g/mol.

• 185 g

• 1350 g

• 10.5 g

What is the mass, in grams, of 0.35 moles of Platinum?

D_Pt = 21.45 g/cm³ MM_Pt = 195.1 g/mol

• 557 g

• 68.3 g

• 7.51 g

Answer explanation

To find the mass of 0.35 moles of Platinum, multiply the number of moles by the molar mass: 0.35 moles × 195.1 g/mol = 68.3 g. Thus, the correct answer is 68.3 g.

Tags

NGSS.HS-PS1-7

What is the volume, in cm³ , of 250 grams of Platinum?

D_Pt = 21.45 g/cm³ MM_Pt = 195.1 g/mol

• 11.7 cm³

• 0.0858 cm³

• 5360 cm³

What is the molar mass (with correct unit & sig figs) for Helium?

• 4.003

• 4 mol/g

• 4.003 moles

• 4.003 g / mol

Answer explanation

The molar mass of Helium is 4.003 g/mol, which indicates the mass of one mole of Helium atoms. The correct unit is grams per mole (g/mol), making '4.003 g / mol' the accurate choice.