AP MCQ 04ABCDEF PART 1

Questions 01-03:

An experiment is conducted in order to determine the mass of silver metal in an alloy. The alloy is dissolved in acid to convert all of the silver metal to silver ions, and those ions are then precipitated by reaction with excess sodium chloride. The precipitate is washed, dried and weighed, and the following data are collected.

Mass of silver alloy = 4.3148 g
Mass of filter paper = 0.50000 g
Mass of filter paper and dried precipitate 1.9332 g

Question 01:

Identify the precipitate and the number of moles of it produced in the gravimetric analysis?

NaCl; 0.010000 mols
NaCl; 1.4332 mols
AgCl; 1.4332 mols
AgCl; 0.010000 mols

Question 02:

What is the % by mass of silver in the alloy?

0.010000 %
1.0787 %
25.000 %
100.00 %

Question 03:

At the end of the experiment it is found that the actual (real) % of silver in the alloy is lower than the % calculated from the experimental data. Which of the following is the most likely explanation for the difference between the actual (real) value, and the calculated value?

Sodium ions were precipitated
Some of the precipitate fell off the filter paper before weighing
The precipitate was not completely dried
The precipitate decomposed during drying, releasing a gas

Question 04:

The complete combustion of one mole of a hydrocarbon in oxygen, yields carbon dioxide and water in a molar ratio of 3CO₂ : 4H₂O. What is a possible formula for the hydrocarbon?

CH₄
C₃H₄
C₃H₈
C₄H₄

Questions 06-07:

When 2.299 g of sodium are brought together with 2.000 g of fluorine and the reaction below occurs.

2Na_(s) + F_2(g) → 2NaF_(s)

Question 05:

What is the maximum mass of sodium fluoride that can be produced?

2.000 g
2.229 g
4.199 g
4.299 g

Question 06:

When the reaction is repeated, this time introducing 1.000 mole of Na metal with 0.5000 moles of F₂ gas, it is found that 21.00 g of NaF are produced. What is the percentage yield in this experiment?

25.00 %
50.00 %
75.00 %
100.0 %

Question 07:

Consider the combustion of ammonia shown in the equation below. Which of the following statements is true in relation to this reaction?

4NH₃ + 5O₂ ⇒ 4NO + 6H₂O

Reacting 4 moles of ammonia with 6 moles of oxygen will yield more products than reacting 4 moles of ammonia with 5 moles of oxygen
Reacting 4 moles of ammonia with 6 moles of oxygen will result in ammonia being left over at the end of the reaction
Reacting 4 moles of ammonia with 6 moles of oxygen will produce a total of 10 moles of products
Reacting 4 moles of ammonia with 6 moles of oxygen will result in no reaction taking place, since the ratio must be 4:5

Question 08:

A 100. mL sample of 0.100 M Li₂CO₃ solution is poured into a beaker that contains to 50.0 mL of 0.300 M Ba(NO₃)₂ solution. A precipitate is observed. Which of the following correctly predicts the contents of the beaker at the end of the reaction?

The precipitate is LiNO₃ and excess barium ions are left in solution
The precipitate is BaCO₃ and excess barium ions are left in solution
The precipitate is LiNO₃ and excess carbonate ions are left in solution
The precipitate is BaCO₃ and excess carbonate ions are left in solution

Question 09:

What type of interaction (force or bond) is changed when solid magnesium chloride is melted?

London dispersion force
Ionic bond
Dipole-dipole force
Covalent bond

Question 10:

Chemical changes always involve the breaking of which type of interaction (force or bond)?

London dispersion forces
Ionic or covalent
Dipole-dipole force
Hydrogen bonds

Question 11:

How might one recognize a change as being purely a physical one?

Only intermolecular forces are broken
Either ionic or covalent bonds are broken
Only ionic bonds are broken
Only covalent bonds are broken

Question 12:

What type of change takes place when solid sodium chloride is dissolved in distilled water?

Only a physical change since only IMF's are broken
Only a chemical change since only ionic bonds are broken
Both chemical & physical since both intra and inter interactions are broken
More data are needed to answer this question

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