practice
basics
1. baking powder is used to raise dough. in baking, it contains a mixture of sodium hydrogen carbonate and tartaric acid.
when baking powder is heated in the oven, a two - step reaction occurs. the word equations for this two - step reaction are given below. carbon dioxide gas is given off in both steps to raise the dough.
step 1:
sodium hydrogen carbonate (stackrel{heat}{
ightarrow}) sodium carbonate + carbon dioxide + water
step 2:
sodium carbonate + tartaric acid (
ightarrow) sodium tartrate + carbon dioxide + x
sodium carbonate has an unpleasant taste, while sodium tartrate has a pleasant taste.
(a) the chemical formula of tartaric acid is (c_4h_6o_6).
complete the table to show the elements and the number of atoms of each element in tartaric acid.
| element | number of atoms |
| ---- | ---- |
| carbon (c) | 4 |
| hydrogen (h) | 6 |
| oxygen (o) | 6 |
(b) name the type of reaction happening in step 1.
(c) optional for 02 science
name substance x that is formed in step 2.
(h_2o)
(d) using the information provided, suggest two reasons why baking powder is used for baking bread (nearly contains tartaric acid).
reason 1: baking powder (contains tartaric acid) reacts to produce carbon dioxide, which makes the dough rise.
reason 2:
(e) state what will be observed if two pieces of litmus paper, red and blue, are placed into tartaric acid separately.
test with red litmus paper:
test with blue litmus paper:

Question

Accepted Answer

### (e) Solution:
# Explanation:
## Step 1: Analyze the reaction in Step 2
The reaction in Step 2 is: sodium carbonate + tartaric acid → sodium tartrate + carbon dioxide + X. We know that in chemical reactions, atoms are conserved (Law of Conservation of Mass). Let's consider the elements involved: Na, C, O, H, and the acid contributes C, H, O.
## Step 2: Deduce the formula of X
Sodium carbonate ($Na_2CO_3$) and tartaric acid ($C_4H_6O_6$) react. The products are sodium tartrate, $CO_2$, and we need to find X. Let's balance the hydrogen and oxygen. The reactants have hydrogen from tartaric acid. When we balance the equation, the remaining atoms for X would be H and O in a ratio of 2:1, which is water ($H_2O$). Also, from the first reaction (Step 1: sodium hydrogen carbonate → sodium carbonate + $CO_2$ + $H_2O$), water is a product, and in Step 2, the pattern of producing water (along with $CO_2$) in acid - carbonate reactions (a type of neutralization or double - displacement) suggests X is water.
# Answer: $H_2O$ (Water)

### (a) Solution:
# Explanation:
## Step 1: Recall the formula of tartaric acid
The chemical formula of tartaric acid is $C_4H_6O_6$.
## Step 2: Fill the table
For the element Carbon (C): The subscript in the formula is 4, so the number of atoms is 4.
For the element Hydrogen (H): The subscript in the formula is 6, so the number of atoms is 6.
For the element Oxygen (O): The subscript in the formula is 6, so the number of atoms is 6.
| Element | Number of atoms |
| ---- | ---- |
| Carbon (C) | 4 |
| Hydrogen (H) | 6 |
| Oxygen (O) | 6 |
# Answer: The completed table has Carbon: 4, Hydrogen: 6, Oxygen: 6.

### (b) Solution:
# Explanation:
## Step 1: Identify the reaction type
The reaction in Step 1 is: sodium hydrogen carbonate $\xrightarrow{heat}$ sodium carbonate + carbon dioxide + water. This is a decomposition reaction because a single compound (sodium hydrogen carbonate) is breaking down into two or more simpler substances (sodium carbonate, carbon dioxide, and water) upon heating.
# Answer: Decomposition reaction

### (d) Solution:
# Brief Explanations:
**Reason 1**: Baking powder contains sodium hydrogen carbonate and tartaric acid. When baking powder is heated (during baking), sodium hydrogen carbonate reacts with tartaric acid to produce carbon dioxide gas ($CO_2$). The carbon dioxide gas gets trapped in the dough, causing the dough to rise and become light and fluffy.
**Reason 2**: Sodium hydrogen carbonate (baking powder component) has a bitter taste, while sodium tartrate (the product of the reaction between sodium carbonate and tartaric acid) has a pleasant taste. So, tartaric acid in baking powder reacts with the sodium hydrogen carbonate (or the sodium carbonate formed from its decomposition) to neutralize the bitter - tasting sodium carbonate/hydrogen carbonate, improving the taste of the baked product.
# Answer:
Reason 1: Baking powder (containing $NaHCO_3$ and tartaric acid) reacts on heating to produce $CO_2$ gas which makes the dough rise (light and fluffy).
Reason 2: Tartaric acid neutralizes the bitter - tasting sodium carbonate (formed from $NaHCO_3$ decomposition) to form pleasant - tasting sodium tartrate, improving the taste of the baked good.

### (e) (the litmus paper test part) Solution:
# Brief Explanations:
Tartaric acid is an acid. Acids have the property of turning blue litmus paper red and having no effect on red litmus paper (red litmus paper remains red in an acidic solution).
- When red litmus paper is dipped in tartaric acid solution: Since tartaric acid is acidic, red litmus paper does not change its color (remains red).
- When blue litmus paper is dipped in tartaric acid solution: Since tartaric acid is acidic, blue litmus paper turns red.
# Answer:
- Test with red litmus paper: Red litmus paper remains red.
- Test with blue litmus paper: Blue litmus paper turns red.

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QUESTION IMAGE

Question

Explanation:

(e) Solution:

Step 1: Analyze the reaction in Step 2

Step 2: Deduce the formula of X

Step 1: Recall the formula of tartaric acid

Step 2: Fill the table

Step 1: Identify the reaction type

Answer:

(a) Solution: