Concentration as molarity

Answer Key - Grade 10 Science Worksheet

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

1. 1.

   43.83 g of salt (58.44 g/mol) is dissolved to make 0.5 L of solution. What is its molarity, to 0.01 M, Bo?

   1.5 M
2. 2.

   171.17 g of sugar (342.34 g/mol) is dissolved to make 0.25 L of solution. What is its molarity, to 0.01 M, Esme?

   2 M
3. 3.

   11.688 g of salt (58.44 g/mol) is dissolved to make 0.4 L of solution. What is its molarity, to 0.01 M, Jun?

   0.5 M
4. 4.

   5.844 g of salt (58.44 g/mol) is in 0.100 L of solution. What is its molarity, Kira?

   • 58.44 M, from 5.844 ÷ 0.100
   • 0.001 M, using 100 L
   • 1.0 M
5. 5.

   11.688 g of salt (58.44 g/mol) is in 250 mL of solution. What is its molarity, Milo?

   • 46.75 M, from 11.688 ÷ 0.250
   • 0.0008 M, using 250 L
   • 0.8 M
6. 6.

   How many moles of salt are in 0.500 L of 0.20 M salt water, Noah?

   • 0.40 mol, from 0.20 ÷ 0.500
   • 0.10 mol
   • 2.5 mol, from 0.500 ÷ 0.20
7. 7.

   How many moles of sugar are in 250 mL of 2.0 M sugar water, Pia?

   • 0.125 mol, from 0.250 ÷ 2.0
   • 0.50 mol
   • 500 mol, using 250 L
8. 8.

   The same 0.2 mol of salt is made into 1 L or into 0.5 L of solution. Which is more concentrated, Tala?

   • They match, since the salt is the same
   • The 1 L solution, since it is the bigger one
   • The 0.5 L solution, at 0.4 M
9. 9.

   Pouring half of a 1.0 M salt solution into another cup does what to its molarity, Zee?

   • It halves to 0.5 M, as half the solution is gone
   • Nothing: each part is still 1.0 M
   • It doubles to 2.0 M
10. 10.

    A pot of 0.3 M sugar water loses some water as steam, but the sugar stays. What happens to its molarity, Ari?

    • It rises, since the same moles sit in less solution
    • It stays 0.3 M, since the sugar is the same
    • It falls, since there is less liquid left in the pot