Question

r×n types & balancing
for each reaction below, balance the equation and identify the type of reaction as either combustion
(combust), single replacement (sr) or double replacement (dr).

1. ____ mgcl₂(aq) + __ na(s) → __ nacl(aq) + __ mg(s) ____
2. ____ h₂o₂ → __ h₂o + __ o₂ ____

Explanation:

Step1: Balance the first equation

For the reaction \(MgCl_{2}(aq)+Na(s)\to NaCl(aq)+Mg(s)\), balance the chlorine atoms first. There are 2 chlorine atoms in \(MgCl_{2}\), so we need 2 \(NaCl\). Then balance the sodium atoms. Since there are 2 \(NaCl\), we need 2 \(Na\).
The balanced equation is \(MgCl_{2}(aq)+2Na(s)\to 2NaCl(aq)+Mg(s)\). This is a single - replacement reaction (SR) because one element (\(Na\)) replaces another element (\(Mg\)) in a compound (\(MgCl_{2}\)).

Step2: Balance the second equation

For the reaction \(H_{2}O_{2}\to H_{2}O + O_{2}\), balance the oxygen atoms. Let's use the least - common - multiple method. The number of oxygen atoms in \(H_{2}O\) is 1 (in the formula \(H_{2}O\)) and in \(O_{2}\) is 2. The least common multiple of 1 and 2 for oxygen (excluding the oxygen in \(H_{2}O_{2}\)) is 2.
If we put a 2 in front of \(H_{2}O_{2}\), we have \(2H_{2}O_{2}\). Then, for the right - hand side, from \(2H_{2}O_{2}\), we get \(2H_{2}O+O_{2}\).
The balanced equation is \(2H_{2}O_{2}\to 2H_{2}O + O_{2}\). This is a decomposition reaction (not in the given types, but if we assume it's a mis - classification and we consider the given types, it's not combustion (no reaction with oxygen to form \(CO_{2}\) and \(H_{2}O\) in a simple sense here), not single or double replacement. But if we follow the problem's instruction to choose from the given types (maybe an error in the problem setup), if we consider the fact that it's not combustion (no fuel - oxygen reaction for the given type definition in the problem), and not double replacement (no exchange of two cations or anions between two compounds). But if we assume it's a non - standard classification and we have to choose from the given, it's not applicable. But if we consider the first reaction's type:

Answer:

1. \(1MgCl_{2}(aq)+2Na(s)\to 2NaCl(aq)+1Mg(s)\), RXN TYPE: SR
2. \(2H_{2}O_{2}\to 2H_{2}O + 1O_{2}\), RXN TYPE: (Not a valid type from the given COMBUST, SR, DR as it is a decomposition reaction. But if forced to choose from the given, no valid choice. However, following the first reaction's classification logic for the first part of the problem):