Question

in the questions below, put a checkmark next to the equations that violate the law of conservation of mass. in simple terms, equations that violate the law are not balanced correctly. check each element!

1. ______ $2h_2 + o_2 \

ightarrow 2h_2o$

1. ______ $na + o_2 \

ightarrow na_2o$

1. ______ $kcl + br_2 \

ightarrow kbr + cl_2$

1. ______ $2h_2 + o_2 \

ightarrow 2h_2o$

1. ______ $na_2co_3 + 2hcl \

ightarrow 2nacl + h_2o + co_2$

1. ______ $4h_2 + 2o_2 \

ightarrow 4h_2o$

1. ______ $2fe_2o_3 + 3c \

ightarrow 4fe + 3co_2$

1. ______ $2h_2 + o_2 \

ightarrow h_2o$

Explanation:

Step 1: Analyze Equation 31 ($\boldsymbol{2H_2 + O_2

ightarrow 2H_2O}$)

• Hydrogen (H): Left side: $2 \times 2 = 4$ atoms. Right side: $2 \times 2 = 4$ atoms. Balanced.
• Oxygen (O): Left side: $2$ atoms. Right side: $2 \times 1 = 2$ atoms. Balanced. So this equation is balanced (no checkmark).

Step 2: Analyze Equation 32 ($\boldsymbol{KCl + Br_2

ightarrow KBr + Cl_2}$)

• Potassium (K): Left: $1$, Right: $1$. Balanced.
• Chlorine (Cl): Left: $1$, Right: $2$. Unbalanced.
• Bromine (Br): Left: $2$, Right: $1$. Unbalanced. So this equation is unbalanced (checkmark).

Step 3: Analyze Equation 33 ($\boldsymbol{Na_2CO_3 + 2HCl

ightarrow 2NaCl + H_2O + CO_2}$)

• Sodium (Na): Left: $2$, Right: $2 \times 1 = 2$. Balanced.
• Carbon (C): Left: $1$, Right: $1$. Balanced.
• Oxygen (O): Left: $3$, Right: $1 + 2 = 3$. Balanced.
• Hydrogen (H): Left: $2 \times 1 = 2$, Right: $2$. Balanced.
• Chlorine (Cl): Left: $2 \times 1 = 2$, Right: $2 \times 1 = 2$. Balanced. So this equation is balanced (no checkmark).

Step 4: Analyze Equation 34 ($\boldsymbol{2Fe_2O_3 + 3C

ightarrow 4Fe + 3CO_2}$)

• Iron (Fe): Left: $2 \times 2 = 4$, Right: $4$. Balanced.
• Oxygen (O): Left: $2 \times 3 = 6$, Right: $3 \times 2 = 6$. Balanced.
• Carbon (C): Left: $3$, Right: $3$. Balanced. So this equation is balanced (no checkmark).

Step 5: Analyze Equation 35 ($\boldsymbol{Na + O_2

ightarrow Na_2O}$)

• Sodium (Na): Left: $1$, Right: $2$. Unbalanced.
• Oxygen (O): Left: $2$, Right: $1$. Unbalanced. So this equation is unbalanced (checkmark).

Step 6: Analyze Equation 36 ($\boldsymbol{2H_2 + O_2

ightarrow 2H_2O}$)

• Same as Equation 31, balanced (no checkmark).

Step 7: Analyze Equation 37 ($\boldsymbol{4H_2 + 2O_2

ightarrow 4H_2O}$)

• Hydrogen (H): Left: $4 \times 2 = 8$, Right: $4 \times 2 = 8$. Balanced.
• Oxygen (O): Left: $2 \times 2 = 4$, Right: $4 \times 1 = 4$. Balanced. So this equation is balanced (no checkmark).

Step 8: Analyze Equation 38 ($\boldsymbol{2H_2 + O_2

ightarrow H_2O}$)

• Hydrogen (H): Left: $2 \times 2 = 4$, Right: $2$. Unbalanced.
• Oxygen (O): Left: $2$, Right: $1$. Unbalanced. So this equation is unbalanced (checkmark).

Answer:

• 31) $\boldsymbol{\times}$ (not unbalanced)
• 32) $\boldsymbol{\checkmark}$ (unbalanced)
• 33) $\boldsymbol{\times}$ (not unbalanced)
• 34) $\boldsymbol{\times}$ (not unbalanced)
• 35) $\boldsymbol{\checkmark}$ (unbalanced)
• 36) $\boldsymbol{\times}$ (not unbalanced)
• 37) $\boldsymbol{\times}$ (not unbalanced)
• 38) $\boldsymbol{\checkmark}$ (unbalanced)