Show All Work In The Space Provided Or Your Answer Is Void

show All Work In The Space Provided Or Your Answer Is Voi

Directions: 1. SHOW ALL WORK in the space provided or your answer is VOID! 1. How many formula units are there in 2.5 moles of MgCl2? A) 2.5 B) 7.5 C) 1.5 × 1024 D) 4.5 × 1024 E) 4.2 × 10–24 Show your work below or ZERO POINTS!

2. How many chloride ions are present in 0.100 mol of MgCl2? A) 0.200 Cl– ions D) 3.32 × 10–25 Cl– ions B) 6.02 × 1022 Cl– ions E) 3.01 × 1024 Cl– ions C) 1.20 × 1023 Cl– ions Show your work below or ZERO POINTS

3. How many nitrate ions are present in 0.200 mol of Zn(NO3)2? A) 1.20 × 1023 NO3– ions D) 6.64 × 10–25 NO3– ions B) 2.41 × 1023 NO3– ions E) 0.400 NO3– ions C) 3.01 × 1024 NO3– ions Show your work below or ZERO POINTS

4. Consider the following chemical equations. Select the equations that represent chemical reactions, rather than physical changes. I. CH4(g) + O2(g) → CO2(g) + H2O(g) II. C2H5OH(l) → C2H5OH(g) III. NaOH(s) → Na+(aq) + OH–(aq) A) I, II, and III D) II and III only B) I and II only E) I only C) I and III only Show your work below or ZERO POINTS

5. Calculate the molar mass of CuSO4·5H2O. A) 159.62 g/mol D) 185.72 g/mol B) 249.70 g/mol E) 446.48 g/mol C) 177.64 g/mol Show your work below or ZERO POINTS

6. If 4.05 × 1023 molecules of a substance have a mass of 86.2 g, what is the molar mass of the substance? A) 128 g/mol D) 4.70 × 1021 g/mol B) 3.49 × 1025 g/mol E) 58.0 g/mol C) 2.13 × 1022 g/mol Show your work below or ZERO POINTS

7. Consider the following chemical equations. Select the equations that represent chemical reactions, rather than physical changes. I. 2NO(g) + O2(g) → 2NO2(g) II. CO2(s) → CO2(g) III. Pb(NO3)2(aq) + 2AgCl(aq) → PbCl2(s) + 2AgNO3(aq) A) I, II, and III D) II and III only B) I and II only E) I only C) I and III only Show your work below or ZERO POINTS

8. Write a complete, balanced equation for the reaction that occurs when sodium metal reacts with water to form hydrogen gas and aqueous sodium hydroxide. A) Na(s) + H2O(l) → NaOH(aq) + H2(g) B) Na(s) + H2O(l) → NaOH(aq) + H2(g) C) Na(s) + 2H2O(l) → NaOH(aq) + 2H2(g) D) Na(s) + 2H2O(l) → 2NaOH(aq) + 2H2(g) E) 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) Show your work below or ZERO POINTS

9. Zinc metal will react with aqueous hydrochloric acid to produce aqueous zinc chloride and hydrogen gas. Write a complete, balanced equation for this reaction. A) Zn(s) + HCl(aq) → ZnCl(aq) + H2(g) B) Zn(s) + HCl(aq) → ZnCl(aq) + H2(g) C) Zn(s) + 2HCl(aq) → ZnCl(aq) + H2(g) D) Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) E) 2Zn(s) + 2HCl(aq) → 2ZnCl(aq) + H2(g) Show your work below or ZERO POINTS

10. Calculate the number of moles of NaHCO3 (sodium bicarbonate, or baking soda) in a 5.0 g sample of this substance. A) 0.096 mole D) 3.6 × 1022 moles B) 0.060 mole E) 2.8 × 1023 mole C) 420 moles Show your work below or ZERO POINTS

11. Calculate the number of moles of NaOH (sodium hydroxide, an ingredient in drain cleaners and oven cleaners) in a 10.0 g sample of this substance. A) 1.51 × 1023 moles D) 4.00 × 102 moles B) 1.66 × 1023 mole E) 0.250 mole C) 0.208 mole Show your work below or ZERO POINTS

12. Calculate the number of moles of CaCO3 (calcium carbonate, or limestone) in a 20.0 g sample of this substance. A) 2.00 × 103 moles D) 1.36 × 103 moles B) 0.200 mole E) 1.20 × 103 moles C) 0.294 mole Show your work below or ZERO POINTS

13. When solid ammonium carbonate is heated, it decomposes to form ammonia gas, carbon dioxide gas, and water vapor, so that the solid completely disappears. Write a complete, balanced equation for this reaction. A) NH4CO3(s) → NH3(g) + CO2(g) + H2O(g) B) NH4CO3(s) → NH2(g) + CO2(g) + H2O(g) C) (NH4)2CO3(s) → NH3(g) + CO2(g) + H2O(g) D) (NH4)2CO3(s) → NH3(g) + CO2(g) + 3H2O(g) E) (NH4)2CO3(s) → 2NH3(g) + CO2(g) + H2O(g) Show your work below or ZERO POINTS

14. Balance the following skeletal equation: C2H5OH(l) + O2(g) → CO2(g) + H2O(g). A) C2H5OH(l) + O2(g) → CO2(g) + 3H2O(g) B) C2H5OH(l) + O2(g) → 2CO2(g) + 3H2O(g) C) C2H5OH(l) + 2O2(g) → 2CO2(g) + 3H2O(g) D) C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(g) E) 2C2H5OH(l) + 3O2(g) → 4CO2(g) + 3H2O(g) Show your work below or ZERO POINTS

15. Balance the following skeletal equation: NH3(g) + O2(g) → NO2(g) + H2O(g). A) 4NH3(g) + 7O2(g) → 4NO2(g) + 6H2O(g) B) 2NH3(g) + 2O2(g) → 2NO2(g) + 3H2O(g) C) 2NH3(g) + O2(g) → NO2(g) + 2H2O(g) D) NH3(g) + O2(g) → NO2(g) + 2H2O(g) E) NH3(g) + O2(g) → NO2(g) + H2O(g) Show your work below or ZERO POINTS

Paper For Above instruction

Balancing chemical equations and understanding the mole concept are fundamental skills in chemistry. This extensive set of problems tests various aspects of these skills, including stoichiometry, ionic and molecular reactions, and chemical reaction classification. Accurate work and correct application of chemical principles are crucial in solving these problems correctly. In this paper, each problem will be tackled with detailed explanations, showing the steps involved in arriving at the solutions, emphasizing good practice in chemical calculations and reasoning.

Question 1: Number of formula units in 2.5 moles of MgCl2

To find the number of formula units in 2.5 moles of MgCl2, use Avogadro's number, which states that 1 mole contains approximately 6.022 × 1023 particles. Therefore, the calculation is:

Number of formula units = 2.5 mol × 6.022 × 1023 units/mol = 1.5055 × 1024 units.

Appropriate choice: C) 1.5 × 1024.

Question 2: Number of chloride ions in 0.100 mol of MgCl2

Each formula unit of MgCl2 contains 2 chloride ions. Therefore, in 0.100 mol of MgCl2, the number of chloride ions is:

0.100 mol × 2 = 0.200 mol of Cl– ions.

Converting to particles: 0.200 mol × 6.022 × 1023 ions/mol = 1.2044 × 1023 ions.

Option: C) 1.20 × 1023 Cl– ions.

Question 3: Nitrate ions in 0.200 mol of Zn(NO3)2

Each formula unit of Zn(NO3)2 contains 2 nitrate ions. So, in 0.200 mol of Zn(NO3)2:

0.200 mol × 2 = 0.400 mol of NO3–.

Particles: 0.400 mol × 6.022 × 1023 ions/mol = 2.4088 × 1023 ions.

Closest option: C) 3.01 × 1024 NO3– ions. (Note: The matching options provided may need correction; calculation shows 2.4 × 1023). For this set, the calculation indicates the correct value is about 2.4 × 1023.

Question 4: Equations representing chemical reactions vs physical changes

Analysis of each equation shows:

  • I. Combustion of methane; chemical reaction.
  • II. Evaporation of ethanol; physical change.
  • III. Dissociation of NaOH into ions; physical change (dissolution), but often considered a physical process.

Usually, dissociation is a physical change; however, ionization of weak acids or bases can be considered chemical reactions. For clarity, in typical chemistry contexts, the dissociation of NaOH is often viewed as a physical process, but since it involves formation of ions, it can be deemed a chemical reaction.

Hence, options: I only, or I and III depending on context. The most accurate: B) I and II only. But given typical classification, the best answer among provided options: B) I and II only.

Question 5: Molar mass of CuSO4·5H2O

Calculations:

  • Copper (Cu): 63.55 g/mol
  • Sulfur (S): 32.07 g/mol
  • Oxygen (O): 16.00 g/mol × 4 + 16.00 g/mol × 5 (from water) = (4 + 5) × 16.00 = 9 × 16.00 = 144.00 g/mol
  • Hydrogen (H): 1.008 g/mol × 10 (from 5 H2O): 10.08 g/mol

Total molar mass = 63.55 + 32.07 + 144.00 + 10.08 = approximately 249.70 g/mol

Answer: B) 249.70 g/mol.

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