Same Stuff or New Stuff: teacher key

Mixing and Reactions, grade 6 edition, written for 6th grade. Some changes make new substances and some do not. Read how scientists tell the difference, from Lavoisier's scales to bubbles, heat, soap and mayonnaise.

Read the book. Print this page for the key.

Questions and answers

1. Which of these is a physical change?
   • Dissolving sugar in coffee (answer)
   • Making rust
   • Baking a cake
2. What is the same all the way through?
   • A layer of oil
   • A solution (answer)
   • A lump of iron
3. Water has a pH of 5. Another sample has a pH of 6. Which is ten times more acidic?
   • The pH 6 water
   • They are the same
   • The pH 5 water (answer)
4. What does egg yolk hold in water to make mayonnaise?
   • Tiny drops of oil (answer)
   • Soap
   • Salt
5. What did Lavoisier find about the mass of products?
   • It is bigger than what went in
   • It equals the mass of what went in (answer)
   • It is smaller than what went in
6. Micelles are groups of what?
   • Metal atoms
   • Gas bubbles
   • Soap molecules (answer)

Words

• physical: no new stuff
• solution: evenly mixed
• micelles: soap balls
• indicator: colour clue
• mass: amount of matter