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Baked Soda for Ramen: Where Did the Missing Grams Go?

Grade 7 physical science: analyze mass data from baking soda heated for ramen noodles and count atoms to show that mass is conserved in a reaction.

Grade 7ScienceInteractive · Printable

Aligned toMS-PS1-5

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What’s included

Single worksheet
Auto-graded online
1 NGSS standard
Printable answer key
9 questions
Classroom-ready

Details

Format: Interactive · Printable
Grade: Grade 7
Subject: Science
Question types: Fill in the blank, Multiple choice, Sorting, Short answer

About this worksheet

What students practice

Students use mass data to show that the mass lost by a solid is carried off by gases formed in a reaction.
Students count atoms in a reaction to show that atoms are rearranged, not created or destroyed.

How to use

Work through Table 1 together, then let students count the atoms in Table 2 on their own. Ask them to name which atoms left the tray before they write the final response.

Curriculum

NGSS standard covered

MS-PS1-5

Model how atoms are rearranged but not created or destroyed in a chemical reaction, so total mass is conserved.

Preview

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Name Date

Baked Soda for Ramen: Where Did the Missing Grams Go?

Follow every atom when baking soda breaks down in an oven.

Baking the soda

Read the passage and Table 1, then answer the questions.

The Secret Ingredient in Ramen

1Seventh grader Lucía Moreno signed up for a Saturday noodle-making class at her community center. The teacher, Chef Daniel Okubo, explained that ramen noodles get their springy bite and yellow color from an alkaline salt mixed into the dough. Ramen shops often buy a liquid called kansui for this, but home cooks can make a similar salt in an ordinary oven from baking soda. Lucía had only ever seen baking soda used in cookies, so she wanted to watch it happen.

2Before class, Chef Okubo spread baking soda in thin layers on three small metal trays, so that the heat could reach all of the powder. Tray B held twice as much as Tray A, and Tray C held half as much. Lucía weighed each tray of powder, and the chef, wearing oven mitts, baked the trays at 150 °C. Every hour, he took the trays out, let them cool and set them on the scale so that Lucía could record the mass of the powder. The powder still looked white, but it felt a little grainier. Lucía was surprised by how much lighter it had become.

3The chef explained that the heat makes baking soda break down in a chemical reaction. The new white solid is sodium carbonate, which cooks call “baked soda.” The reaction also forms two gases, water vapor and carbon dioxide, which drift out of the oven. He wrote the reaction on the board: 2 NaHCO₃ → Na₂CO₃ + H₂O + CO₂. Lucía's science teacher later worked out that for every 42.0 g of baking soda, this reaction forms 4.5 g of water.

4The chef stores his baked soda in a tightly closed jar and wears gloves when he measures it, because it can irritate skin. He told the class that baked soda left in an open dish on a humid day slowly gets heavier. Only a few grams dissolved in water are needed for a whole batch of noodle dough.