Question

practice
1 basic
baking powder is used for inner doughs in baking. it contains a mixture of sodium bicarbonate, tartaric acid and tartrate salts.
the two-step reaction occurs. the word equations for these two steps are given below.
step 1:
sodium hydrogen carbonate → sodium carbonate + carbon dioxide + x
step 2:
sodium carbonate + tartaric acid → sodium tartrate + carbon dioxide + water
sodium carbonate has an unpleasant taste, while sodium tartrate has a pleasant taste.
(a) the chemical formula of tartaric acid is c₄h₆o₆.
complete the table to show the elements and the number of atoms of each element in tartaric acid.
element | number of atoms
carbon (c) |
hydrogen (h) |
oxygen (o) |
(b) name the type of reaction happening in step 1.
(c) optional (for g2 science)
name substance x that is formed in step 2.
(d) using the information provided, suggest two reasons why baking powder is used for
baking bread (mainly contains tartaric acid).
reason 1
reason 2
(e) state what will be observed if two pieces of litmus paper, red and blue, are placed into tartaric acid separately.
test using red litmus paper
test using blue litmus paper

Answer:

(p) - Step-by-Step Explanation (Chemistry, a subfield of Natural Science)

Step 1: Identify Reactants and Products in Step 1

In Step 1, the reaction is: Sodium hydrogen carbonate + tartaric acid → Sodium tartrate + Carbon dioxide + X. Wait, no, wait—wait, the first reaction (Step 1) is: Sodium hydrogen carbonate → Sodium carbonate + Carbon dioxide + Water? Wait, no, the image shows: "Step 1: sodium hydrogen carbonate → sodium carbonate + carbon dioxide + X" (wait, maybe misread). Wait, actually, the reaction in Step 1: Let's check the reaction type. Sodium hydrogen carbonate (a base) reacting with tartaric acid (an acid)? Wait, no, Step 1: "sodium hydrogen carbonate → sodium carbonate + carbon dioxide + X"—wait, maybe decomposition? Wait, no, the other reaction: "sodium carbonate + tartaric acid → sodium tartrate + carbon dioxide + X" (Step 2). Wait, for part (p): "Name the type of reaction happening in step 1". Let's re-express Step 1: Sodium hydrogen carbonate decomposes? Wait, no, the first reaction (Step 1) is: Sodium hydrogen carbonate → Sodium carbonate + Carbon dioxide + Water? Wait, the formula for sodium hydrogen carbonate is \( \text{NaHCO}_3 \), sodium carbonate is \( \text{Na}_2\text{CO}_3 \), carbon dioxide \( \text{CO}_2 \), and water \( \text{H}_2\text{O} \). But the reaction for Step 1: Let's balance. \( 2\text{NaHCO}_3
ightarrow \text{Na}_2\text{CO}_3 + \text{CO}_2 + \text{H}_2\text{O} \). This is a decomposition reaction? Wait, no, decomposition is one reactant forming multiple products. But \( \text{NaHCO}_3 \) decomposing into \( \text{Na}_2\text{CO}_3 \), \( \text{CO}_2 \), and \( \text{H}_2\text{O} \). Alternatively, maybe a reaction with acid? Wait, no, Step 1's reactant is sodium hydrogen carbonate, product is sodium carbonate, CO₂, and X (which in (r) is H₂O). So the reaction is \( 2\text{NaHCO}_3
ightarrow \text{Na}_2\text{CO}_3 + \text{CO}_2 + \text{H}_2\text{O} \). This is a decomposition reaction (one compound breaking into multiple compounds). Alternatively, if it's reacting with tartaric acid, but Step 1's reactant is sodium hydrogen carbonate. Wait, maybe the first reaction is decomposition of sodium hydrogen carbonate. So the type of reaction in Step 1 is decomposition (or maybe acid-base, but no—wait, Step 2 is sodium carbonate + tartaric acid (acid) → sodium tartrate (salt) + CO₂ + H₂O, which is acid-base (neutralization) producing salt, CO₂, and H₂O. But Step 1: sodium hydrogen carbonate → sodium carbonate + CO₂ + H₂O. So decomposition: a single compound breaks down into two or more simpler substances. So the reaction type is decomposition (or maybe thermal decomposition, as baking powder reactions involve heat).

Step 2: Confirm Reaction Type

Decomposition reactions have one reactant and multiple products. Here, \( \text{NaHCO}_3 \) (reactant) forms \( \text{Na}_2\text{CO}_3 \), \( \text{CO}_2 \), and \( \text{H}_2\text{O} \) (products). So the reaction type is decomposition (or more specifically, thermal decomposition, but generally decomposition).

(r) - Step-by-Step Explanation

Step 1: Analyze Step 2 Reaction

Step 2: Sodium carbonate + tartaric acid → Sodium tartrate + Carbon dioxide + X. The chemical formula of tartaric acid is \( \text{C}_4\text{H}_6\text{O}_6 \) (from part (q)). Sodium carbonate is \( \text{Na}_2\text{CO}_3 \). The products are sodium tartrate (salt), \( \text{CO}_2 \), and X. In acid-base reactions (neutralization) with carbonates, the products are salt, \( \text{CO}_2 \), and \( \text{H}_2\text{O} \). Let's balance the reaction: \( \text{Na}_2\text{CO}_3 + \text{C}_4\text{H}_6\text{O}_6
ightarrow \text{Na}_2\text{C}_4\text{H}_4\text{O}_6 \) (sodium tartrate) + \( \text{CO}_2 + \text{H}_2\text{O} \). Balancing: Left side: Na: 2, C: 1 + 4 = 5, H: 6, O: 3 + 6 = 9. Right side: Na: 2, C: 4 + 1 = 5, H: 2 (from H₂O) + 4 (from tartrate) = 6? Wait, sodium tartrate is \( \text{Na}_2\text{C}_4\text{H}_4\text{O}_6 \) (so H: 4), CO₂: 1 (C:1, O:2), H₂O: 1 (H:2, O:1). So total C: 4 + 1 = 5, H: 4 + 2 = 6, O: 6 + 2 + 1 = 9. Which matches left side. So X is \( \text{H}_2\text{O} \) (water). Alternatively, from Step 1, X was H₂O, and Step 2 also produces H₂O. So substance X formed in Step 2 is water (\( \text{H}_2\text{O} \)).

(p) Answer:

The reaction in Step 1 is a decomposition reaction (or thermal decomposition, as sodium hydrogen carbonate decomposes into sodium carbonate, carbon dioxide, and water).

(r) Answer:

Substance X formed in Step 2 is water (chemical formula \( \text{H}_2\text{O} \)).