Question

examine the statement.
potassium reacts with magnesium bromide to form potassium bromide and magnesium.
which equation correctly represents the statement?
○ 2k + mgbr₂ → 2kbr + mg
○ k + mgbr₂ → kbr₂ + mg
○ 2kbr + mg → 2k + mgbr₂
○ k + mgbr → kbr + mg

Explanation:

Step1: Check the formula of magnesium bromide

Magnesium has a \(+2\) charge (\(Mg^{2+}\)), bromide has a \(-1\) charge (\(Br^{-}\)). So the formula of magnesium bromide is \(MgBr_{2}\), not \(MgBr\). So the option \(K + MgBr
ightarrow KBr+Mg\) is wrong.

Step2: Check the formula of potassium bromide

Potassium has a \(+1\) charge (\(K^{+}\)), bromide has a \(-1\) charge (\(Br^{-}\)). The formula of potassium bromide is \(KBr\), not \(KBr_{2}\). So the option \(K + MgBr_{2}
ightarrow KBr_{2}+Mg\) is wrong.

Step3: Check the reaction direction

The reaction is potassium reacting with magnesium bromide, so potassium and magnesium bromide are reactants. The option \(2KBr + Mg
ightarrow 2K+MgBr_{2}\) has potassium bromide and magnesium as reactants, which is wrong.

Step4: Check the balance of the equation \(2K + MgBr_{2}

ightarrow 2KBr+Mg\)

• For potassium (\(K\)): Left - hand side has \(2\) atoms (from \(2K\)), right - hand side has \(2\) atoms (from \(2KBr\)).
• For magnesium (\(Mg\)): Left - hand side has \(1\) atom (from \(MgBr_{2}\)), right - hand side has \(1\) atom (from \(Mg\)).
• For bromine (\(Br\)): Left - hand side has \(2\) atoms (from \(MgBr_{2}\)), right - hand side has \(2\) atoms (from \(2KBr\)).

Answer:

\(2K + MgBr_{2}
ightarrow 2KBr + Mg\) (the first option)