Why things dissolve: polarity, electrolytes and nonelectrolytes

Answer Key - Grade 10 Science Worksheet

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

1. 1.

   A cup holds 1 mol of dissolved sugar and 1 mol of dissolved salt. How many moles of dissolved particles is that, Bo?

   3 mol
2. 2.

   A cup holds 0.5 mol of dissolved sugar and 0.25 mol of dissolved salt. How many moles of dissolved particles is that, Esme?

   1 mol
3. 3.

   In salt water, what are the dissolved particles, Luz?

   • Tiny drops of melted salt
   • Whole NaCl units
   • Separate Na⁺ and Cl⁻ ions
4. 4.

   Why can water pull salt apart, Milo?

   • Its heat melts the salt crystal
   • It cuts the salt into whole NaCl pieces
   • Its charged ends attract the ions
5. 5.

   What happens to sugar as it dissolves, Noah?

   • Its molecules split into charged ions, like salt
   • It melts into syrup
   • Its molecules spread apart but stay whole
6. 6.

   1 mol of sugar dissolves in water. How many moles of dissolved particles form, Pia?

   • 0 mol, since the sugar melts away
   • 2 mol, since sugar splits like salt
   • 1 mol, since sugar stays whole
7. 7.

   Why does sugar dissolve in water even though it forms no ions, Ren?

   • Sugar melts in water
   • Sugar is polar enough to attract water
   • Sugar does form ions in water
8. 8.

   A tester lights brightly in salt water, dimly in circle water and not at all in sugar water. Which holds the most ions, Tala?

   • The salt water
   • The sugar water
   • They hold the same ions
9. 9.

   Why does circle water light the tester a little, Zee?

   • Water molecules themselves split into many ions in the tap
   • It holds a few dissolved ions from minerals
   • Dissolved sugar in it forms ions
10. 10.

    Baking soda water lights the tester. What does that show, Ari?

    • Baking soda forms ions: it is an electrolyte
    • Baking soda stays as whole molecules
    • Baking soda melted in the water