Question

unit 5 quiz 1
miller, z. chemistry a_section 1_fall 25/26 / unit 5 - chemical reactions
when the following equation is balanced, what is the coefficient for libr?
\underline{\quad\quad} f₂(g) + \underline{\quad\quad} libr(aq) → \underline{\quad\quad} lif(s) + \underline{\quad\quad} br₂(l)
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1. choose the best answer.

when the following equation is balanced, what is the coefficient for k₂so₄?
\underline{\quad\quad} albr₃ + \underline{\quad\quad} k₂so₄ → \underline{\quad\quad} kbr + \underline{\quad\quad} al₂(so₄)₃
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Explanation:

First Question (LiBr Coefficient)

Step1: Balance Br atoms

On the right, \( \text{Br}_2 \) has 2 Br atoms. On the left, \( \text{LiBr} \) has 1 Br atom. So we need 2 \( \text{LiBr} \) to balance Br: \( \text{F}_2 + 2\text{LiBr}
ightarrow \text{LiF} + \text{Br}_2 \)

Step2: Balance Li and F atoms

Now, 2 \( \text{LiBr} \) gives 2 Li. So \( \text{LiF} \) needs a coefficient of 2. For F: left has \( \text{F}_2 \) (2 F), right has 2 \( \text{LiF} \) (2 F). Now check all: \( \text{F}_2 + 2\text{LiBr}
ightarrow 2\text{LiF} + \text{Br}_2 \). All atoms (F: 2, Li: 2, Br: 2) are balanced.

Step1: Balance Al atoms

Right has \( \text{Al}_2(\text{SO}_4)_3 \) (2 Al), left has \( \text{AlBr}_3 \) (1 Al). So \( \text{AlBr}_3 \) needs coefficient 2: \( 2\text{AlBr}_3 + \text{K}_2\text{SO}_4
ightarrow \text{KBr} + \text{Al}_2(\text{SO}_4)_3 \)

Step2: Balance SO₄²⁻ ions

Right has \( \text{Al}_2(\text{SO}_4)_3 \) (3 \( \text{SO}_4^{2-} \)), left has \( \text{K}_2\text{SO}_4 \) (1 \( \text{SO}_4^{2-} \)). So \( \text{K}_2\text{SO}_4 \) needs coefficient 3: \( 2\text{AlBr}_3 + 3\text{K}_2\text{SO}_4
ightarrow \text{KBr} + \text{Al}_2(\text{SO}_4)_3 \)

Step3: Balance K and Br atoms

Now, 3 \( \text{K}_2\text{SO}_4 \) gives 6 K. So \( \text{KBr} \) needs coefficient 6. 2 \( \text{AlBr}_3 \) gives 6 Br, which matches 6 \( \text{KBr} \). Check all: \( 2\text{AlBr}_3 + 3\text{K}_2\text{SO}_4
ightarrow 6\text{KBr} + \text{Al}_2(\text{SO}_4)_3 \). Al: 2, Br: 6, K: 6, \( \text{SO}_4^{2-} \): 3. Balanced.

Answer:

2

Second Question (K₂SO₄ Coefficient)