Molar mass and converting grams to moles

Answer Key - Grade 10 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   A sample of water (H₂O: 2 H at 1.01 g/mol, 1 O at 16 g/mol) has a mass of 27.03 g. How many moles is it, to 0.01 mol, Esme?

   1.5 mol
2. 2.

   A sample of CO₂ (1 C at 12.01 g/mol, 2 O at 16 g/mol) has a mass of 132.03 g. How many moles is it, to 0.01 mol, Jun?

   3 mol
3. 3.

   A spoon of water (H₂O: 2 H at 1.01 g/mol, 1 O at 16 g/mol) has a mass of 9.01 g. How many moles is it, to 0.01 mol, Kira?

   0.5 mol
4. 4.

   Pia says 10 g of salt and 10 g of sugar hold the same number of moles. Which reply fits, Milo?

   • Agree: equal grams mean equal moles for any substance
   • Disagree: salt's smaller molar mass gives more moles
   • Disagree: the sugar holds more moles, as it is heavier
5. 5.

   Luz says that to change grams into moles you multiply by 6.022 × 10²³. Which reply fits, Noah?

   • Agree, as long as the sample is water
   • Disagree: divide the grams by the molar mass
   • Agree: Avogadro's number links grams and moles
6. 6.

   How many molecules are in 18.02 g of water, Pia?

   • 1 molecule
   • 1.085 × 10²⁵ molecules
   • 6.022 × 10²³ molecules
7. 7.

   How many molecules are in 9.01 g of water, Ren?

   • 5.426 × 10²⁴ molecules
   • 1.2044 × 10²⁴ molecules
   • 3.011 × 10²³ molecules
8. 8.

   How many molecules are in 88.02 g of CO₂, Tala?

   • 5.301 × 10²⁵ molecules
   • 1.2044 × 10²⁴ molecules
   • 3.011 × 10²³ molecules
9. 9.

   Which holds more moles: 10 g of salt or 10 g of sugar, Zee?

   • They match, since the masses are equal
   • The salt, since its molar mass is smaller
   • The sugar, since its molar mass is larger
10. 10.

    Which holds the most moles: 100 g of water, 100 g of salt or 100 g of glucose, Bo?

    • They match, since each is 100 g
    • The glucose, about 0.56 mol
    • The water, about 5.55 mol