Question

quiz 8.6be- counting atoms, chemical equations and the law of conservation of mass 3 of 10 possible points: 6.25 the table shows various chemical formulas. i. co(no₃)₂ ii. (nh₄)₂co₃ iii. (nh₄)₃po₄ iv. al(no₂)₃ v. nh₄no₃ which of these formulas contain equal numbers of nitrogen atoms? ○ formulas i and iv ○ formulas ii and iii ○ formulas i, ii, and v ○ formulas i and iii

Explanation:

Step1: Count N in Formula I

Formula I: $\ce{Co(NO_{3})_{2}}$. Inside the parentheses, $\ce{NO_{3}}$ has 1 N, and the subscript outside is 2. So N atoms: $1\times2 = 2$.

Step2: Count N in Formula II

Formula II: $\ce{(NH_{4})_{2}CO_{3}}$. Inside the parentheses, $\ce{NH_{4}}$ has 1 N, subscript outside is 2. N atoms: $1\times2 = 2$.

Step3: Count N in Formula III

Formula III: $\ce{(NH_{4})_{3}PO_{4}}$. Inside the parentheses, $\ce{NH_{4}}$ has 1 N, subscript outside is 3. N atoms: $1\times3 = 3$.

Step4: Count N in Formula IV

Formula IV: $\ce{Al(NO_{2})_{3}}$. Inside the parentheses, $\ce{NO_{2}}$ has 1 N, subscript outside is 3. N atoms: $1\times3 = 3$.

Step5: Count N in Formula V

Formula V: $\ce{NH_{4}NO_{3}}$. There are two N atoms (one in $\ce{NH_{4}^+}$, one in $\ce{NO_{3}^-}$). N atoms: $1 + 1 = 2$.

Step6: Compare N counts

• Formula I: 2 N
• Formula II: 2 N
• Formula V: 2 N

So Formulas I, II, and V have equal N atoms.

Answer:

Formulas I, II, and V