The table below shows the masses of some elements. Find the mass of each compound above.

Question

Element
Mass of an Atom (amu)
Element
Mass of an Atom (amu)
Mg
24
Na
23
Cl
35
Br
80
H
1
O
16

Mass of MgCl2: ____________
Mass of NaBr: _____________Mass of H2O: _____________

Answer 1

To calculate the mass of each compound, we need to consider the number of atoms of each element in the compound and their respective atomic masses.

1. Mass of MgCl₂:

   • Magnesium (Mg): 1 atom × 24 amu = 24 amu
   • Chlorine (Cl): 2 atoms × 35 amu = 70 amu
   • Total mass of MgCl₂ = 24 amu + 70 amu = 94 amu

2. Mass of NaBr:

   • Sodium (Na): 1 atom × 23 amu = 23 amu
   • Bromine (Br): 1 atom × 80 amu = 80 amu
   • Total mass of NaBr = 23 amu + 80 amu = 103 amu

3. Mass of H₂O:

   • Hydrogen (H): 2 atoms × 1 amu = 2 amu
   • Oxygen (O): 1 atom × 16 amu = 16 amu
   • Total mass of H₂O = 2 amu + 16 amu = 18 amu

Final Answers:

• Mass of MgCl₂: 94 amu
• Mass of NaBr: 103 amu
• Mass of H₂O: 18 amu

Answer 2

For each of the expressions below, can you find the total number of atoms represented?
2MgCl2 How many- Mg: ______ Cl: _______ Total Atoms: ________
NaBr How many- Na: _____ Br: _______ Total Atoms: _________
4H2O How many- H: ______ O: ______ Total Atoms: ________
Mass of MgCl2: ____________
Mass of NaBr: _____________
Mass of H2O: _____________

Answer 3

Let's break down each of the expressions to find the total number of atoms for each compound.

1. For \(2\text{MgCl}_2\):

• Mg:

  • There are 2 molecules, each contains 1 Mg atom:
  • \(2 \text{Mg} = 2 \times 1 = 2 \text{ Mg atoms}\)

• Cl:

  • Each molecule contains 2 Cl atoms:
  • \(2 \text{MgCl}_2 = 2 \times 2 = 4 \text{ Cl atoms}\)

• Total Atoms:

  • Total = \(2 \text{ (Mg)} + 4 \text{ (Cl)} = 6 \text{ total atoms}\)

Summary for \(2\text{MgCl}_2\):

• Mg: 2
• Cl: 4
• Total Atoms: 6

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2. For \(\text{NaBr}\):

• Na:

  • There is 1 Na atom:
  • \(1 \text{Na} = 1 \text{ Na atom}\)

• Br:

  • There is 1 Br atom:
  • \(1 \text{Br} = 1 \text{ Br atom}\)

• Total Atoms:

  • Total = \(1 \text{ (Na)} + 1 \text{ (Br)} = 2 \text{ total atoms}\)

Summary for \(\text{NaBr}\):

• Na: 1
• Br: 1
• Total Atoms: 2

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3. For \(4\text{H}_2\text{O}\):

• H:

  • Each H₂O molecule contains 2 H atoms:
  • \(4 \text{H}_2\text{O} = 4 \times 2 = 8 \text{ H atoms}\)

• O:

  • Each H₂O molecule contains 1 O atom:
  • \(4 \text{H}_2\text{O} = 4 \times 1 = 4 \text{ O atoms}\)

• Total Atoms:

  • Total = \(8 \text{ (H)} + 4 \text{ (O)} = 12 \text{ total atoms}\)

Summary for \(4\text{H}_2\text{O}\):

• H: 8
• O: 4
• Total Atoms: 12

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Total Masses (As Previously Calculated):

• Mass of \(\text{MgCl}_2\): 94 amu
• Mass of \(\text{NaBr}\): 103 amu
• Mass of \(\text{H}_2\text{O}\): 18 amu

Final Summary:

• \(2\text{MgCl}_2\):

  • Mg: 2,
  • Cl: 4,
  • Total Atoms: 6

• \(\text{NaBr}\):

  • Na: 1,
  • Br: 1,
  • Total Atoms: 2

• \(4\text{H}_2\text{O}\):

  • H: 8,
  • O: 4,
  • Total Atoms: 12

• Mass of \(\text{MgCl}_2\): 94 amu

• Mass of \(\text{NaBr}\): 103 amu

• Mass of \(\text{H}_2\text{O}\): 18 amu

Answer 4

In which chemical equation is the number of atoms in the reactants the same as the number of atoms in the products?(1 point)
Responses

Zn + 2HCl → H2 + ZnCl2
Zn + 2HCl → H 2 + ZnCl 2

CH4 + O2 → CO2 + 2H2O
CH 4 + O 2 → CO 2 + 2H 2 O

CO2 + H2O → CH2OH + O2
CO 2 + H 2 O → CH 2 OH + O 2

Li2CO3 → LiO + CO2

Answer 5

To determine the chemical equation in which the number of atoms in the reactants is the same as the number of atoms in the products, we need to balance each equation and count the total number of atoms on both sides.

1. Equation: \( \text{Zn} + 2\text{HCl} \rightarrow \text{H}_2 + \text{ZnCl}_2 \)

   • Reactants:
     • Zn: 1
     • H: 2
     • Cl: 2
     • Total: 1 + 2 + 2 = 5 atoms
   • Products:
     • H: 2
     • Zn: 1
     • Cl: 2
     • Total: 2 + 1 + 2 = 5 atoms
   • Conclusion: Balanced (5 atoms on both sides).

2. Equation: \( \text{CH}_4 + \text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} \)

   • Reactants:
     • C: 1
     • H: 4
     • O: 2
     • Total: 1 + 4 + 2 = 7 atoms
   • Products:
     • C: 1
     • H: 4
     • O: 3
     • Total: 1 + 4 + 3 = 8 atoms
   • Conclusion: Not balanced.

3. Equation: \( \text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{CH}_2\text{OH} + \text{O}_2 \)

   • Reactants:
     • C: 1
     • O: 3
     • H: 2
     • Total: 1 + 3 + 2 = 6 atoms
   • Products:
     • C: 1
     • H: 2
     • O: 3
     • Total: 1 + 2 + 3 = 6 atoms
   • Conclusion: Balanced (6 atoms on both sides).

4. Equation: \( \text{Li}_2\text{CO}_3 \rightarrow \text{LiO} + \text{CO}_2 \)

   • Reactants:
     • Li: 2
     • C: 1
     • O: 3
     • Total: 2 + 1 + 3 = 6 atoms
   • Products:
     • Li: 1
     • C: 1
     • O: 3
     • Total: 1 + 1 + 3 = 5 atoms
   • Conclusion: Not balanced.

Final Conclusion:

The balanced chemical equations where the number of atoms in the reactants is the same as the number of atoms in the products are:

• \( \text{Zn} + 2\text{HCl} \rightarrow \text{H}_2 + \text{ZnCl}_2 \)
• \( \text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{CH}_2\text{OH} + \text{O}_2 \)

If a single answer is required, you may choose either of the first two.

Correct answers:

• 1st option: \( \text{Zn} + 2\text{HCl} \rightarrow \text{H}_2 + \text{ZnCl}_2 \)
• 3rd option: \( \text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{CH}_2\text{OH} + \text{O}_2 \)