8th grade Mass stays the same in a reaction worksheet

Mass stays the same in a reaction

Grade 8 Science Worksheet

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

1. 1.

   Bo's teacher mixes 130 g of one solution with a second solution in a sealed jar. The products total 200 g. What was the mass of the second solution?
2. 2.

   Before, iron 56 g and oxygen ? g; after, rust 80 g. Jun reads the table for steel wool rusting in a sealed jar. How much oxygen joined the iron?
3. 3.

   Before, copper 64 g and oxygen ? g; after, copper oxide 80 g. A teacher heats copper powder in a sealed tube and it turns into black copper oxide. Using the table, how much oxygen joined the copper, Kira?
4. 4.

   Before, hydrogen peroxide 68 g; after, water 36 g and oxygen ? g. In a teacher's sealed flask, yeast helps hydrogen peroxide break down into water and oxygen. Using the table, how much oxygen formed, Luz?
5. 5.

   Milo leaves steel wool in an open dish on a scale. Over days it rusts and the reading goes up. Why?

   • Rust is new matter made in the dish
   • Oxygen from the air joined the iron
   • The dish got heavier by itself
   • Water evaporated from the dish
6. 6.

   Noah's book says a burned log leaves ash that weighs far less than the log. Where did most of the mass go?

   • It was destroyed by the burning
   • Into gases, which weigh nothing
   • Into the ground under the fire
   • Into the air as gases
7. 7.

   A fizzing tablet in an open cup makes the scale drop by 4 g. Where did the 4 g go, Pia?

   • Into the cup's walls
   • Into the air as carbon dioxide gas
   • Nowhere: gas bubbles weigh nothing
   • It was used up by the fizzing
8. 8.

   Ren graphs the same fizzing reaction twice: once in an open cup (line P) and once in a sealed bottle (line Q). Which line shows conservation of mass?

   • Line P: its mass changed, so it reacted more
   • Both lines equally
   • Line Q: nothing could escape
   • Neither: mass drops in reactions
9. 9.

   In Tala's open-cup graph, the mass falls from 300 g to 296 g. What was the mass of the gas that escaped?

   • 0 g: gases weigh nothing
   • 296 g
   • 300 g
   • 4 g
10. 10.

    Zee's open dish of steel wool rusts, and its mass rises from 150 g to 153 g. How much oxygen joined from the air?

    • 153 g
    • 3 g
    • 303 g
    • 0 g: air adds no mass