SME
Grade 5 Science · Problem type
Gas that escaped from a fizz
Use this for “The cup weighed less after the fizz. Where did the mass go?”
Diagram
140 g − 137 g = 3 g.
That is the gas that escaped.
Gas that escaped: 3 g
This is an example. Type your own values to start a new problem.
Baking soda (g)
+
Vinegar (g)
+
Cup (g)
=
Total before (g)
Total before (g)
−
Total after (g)
=
Gas that escaped (g)
Formulas
10 + 100 + 30 = 140
Baking soda + vinegar + cup = total before
140 − 137 = 3
Total before − total after = gas that escaped
Assumptions
•
Baking soda and vinegar make a gas: the fizz.
•
In an open cup the gas escapes into the air, so the scale reads less.
•
In a sealed bag the gas stays, and the mass does not change.
Step-by-step
WE KNOW
Baking soda: 10 g
Vinegar: 100 g
Cup: 30 g
Total after: 137 g
FIND
total before, gas that escaped
Step 1 · Find total before
10 + 100 + 30 = ?
Baking soda + vinegar + cup = total before
Add up all the masses on the scale.
Total before = 140 g
Step 2 · Find gas that escaped
140 − 137 = ?
Total before − total after = gas that escaped
The mass that is missing after the fizz is the gas that escaped into the air.
Gas that escaped = 3 g
Check
Put the numbers back in. Both sides should match.
10 + 100 + 30 = 140 ✓
140 − 137 = 3 ✓
Topic check
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