# UOFM Grams Moles and Numbers Questions

1. How many atoms of hydrogen are in (4.5×10^-2) moles of hydrogen (H)?

For Avogadro’s number use: 6.022 x 1023

Round your answer to two significant figures.

Enter your answer using scientific notation. (Ignore the red words you see below)

Include the correct unit

.

2. How many neon atoms are contained in (8.85×10^2) grams of neon?

Use at least two decimal places for the molar mass.

Report your answer in scientific notation to the correct number of significant figures.

3.

How many grams of rubidium are in 2.37 x 1024 atoms of rubidium?

Enter your answer in decimal form with the correct number of sig figs. Use the proper abbreviation for the units.

4.

Calculate the mass (in grams) of 4.17 x 1022 carbon atoms.

Round your answer to two decimal places.

5.

This is an impossible formula. Pretend it is real.

If you had 1 mol of Cr4(PO4)2 how many moles of Cr would there be?

Remember that you should never include a 1 as a subscript but for the sake of clarity for this problem you may see a 1 as a subscript.

Fe = 52.00 g/mol

P = 30.97 g/mol

O = 16.00 g/mol

Make sure your answer includes **TWO decimal place**s.**6.**This is an impossible formula. Pretend it is real.

If you had 1 mol of Mn8(ClO4)3 how many moles of Cl would there be?

Remember that you should never include a 1 as a subscript but for the sake of clarity for this problem you may see a 1 as a subscript.Make sure your answer includes **TWO decimal places.****7.**

This is an impossible formula. If it were real, determine the molar mass of:

Fe3S5O4

Remember that you should never include a 1 as a subscript but for the sake of clarity for this problem you may see a 1 as a subscript.

Fe = 55.85 g/mol

Si = 32.06 g/mol

O = 16.00 g/molMake sure your answer includes TWO decimal places.**8.**This is an impossible formula. If it were real, determine the molar mass of:

Cr7(PO4)3

Remember that you should never include a 1 as a subscript but for the sake of clarity for this problem you may see a 1 as a subscript.Fe = 52.00 g/molP = 30.97 g/molO = 16.00 g/molMake sure your answer includes TWO decimal place**9.**

The molar mass (to two decimal places) for Fe2(CO3)3 is

10. This is an impossible formula. If it were real, determine the molar mass of:

KBr•6H2O

K = 39.10 g/mol

Br = 79.90 g/mol

(Hopefully your remember water’s)

Make sure your answer includes TWO decimal places.**11.**

How many molecules of hydrogen fluoride (HF) are in (8.1×10^-2) moles of hydrogen fluoride (HF)?

For Avogadro’s number use: 6.022 x 1023Round your answer to two significant figures.

For the unit, use the word molecule.

12.

How many moles of sodium chloride (NaCl) are in (6.21×10^-41) molecules of sodium chloride (NaCl)?

Question Information

For Avogadro’s number use: 6.022 x 1023

Round your answer to three significant figures.

*On this problem if you do not EITHER: Use your exponent key OR put parenthesis around your entire denominator, you will get the wrong answer.*

Enter your answer using scientific notation. (Ignore the red words you see below)Include the correct unit13. A student weighs out 23.21 grams of sodium permanganate, NaMnO4. How many moles of NaMnO4 is this? The molar mass of NaMnO4 is 141.93 g/mol. Use the standard abbreviation for the units.14. Selenium dichloride, SeCl2, has a molar mass of 149.86 g/mol. What is the mass in grams of 0.415 moles of SeCl2? Use the common abbreviation for the units.15. How many grams of KI are in 5.30 x 1022 molecules of potassium iodide (KI)?**Additional Information:**

If needed, Molar Mass of KI is 166.00 g/mol

If needed, use the periodic chart values from the printable Periodic chart provided with this course.

If needed use 6.022 x 1023 for Avogadro’s number.

**Format your answer:**

With three significant figures

Include the correct unit.

Enter your answer in decimal form with 3 sig figs. Use the proper abbreviation for the units.

16.

How many grams of MgBr2 are in 5.57 x 1022 molecules of magnesium bromide (MgBr2)?Mg = 24.01 g/molBr = 79.90 g/molAdditional Information:

If needed, use the periodic chart values from the printable Periodic chart provided with this course.If needed use 6.022 x 1023 for Avogadro’s number.