Question

1. the initial mixture of all four substances can be classified as a __ mixture, and the final mixture of alcohol and substance d can be classified as a __ mixture.

(a) heterogeneous; heterogeneous
(b) homogeneous; homogeneous
(c) homogeneous; heterogeneous
(d) heterogeneous; homogeneous
each substance in the table below corresponds to one of the unknown substances, a - d.

1. based on the data table above, which of the following sets correctly pairs each unknown substance letter with the appropriate identity?

(a) a = neodymium powder, b = ammonium chloride, c = benzoic acid, d = lead chloride
(b) a = lead chloride, b = benzoic acid, c = neodymium powder, d = ammonium chloride
(c) a = ammonium chloride, b = lead chloride, c = neodymium powder, d = benzoic acid
(d) a = benzoic acid, b = lead chloride, c = neodymium powder, d = ammonium chloride

Explanation:

15.

Step1: Analyze the initial mixture

The initial mixture has four substances with different physical properties (different colors, odors etc.). A heterogeneous mixture has visibly different parts. So the initial mixture is heterogeneous.

Step2: Analyze the final mixture (alcohol and substance D)

Alcohol is a liquid. If substance D (lead (II) chloride) is mixed with alcohol, since lead (II) chloride is insoluble in alcohol (from the table: “insoluble in alcohol” for \(PbCl_2\)), the mixture will have two - phase (solid and liquid). A heterogeneous mixture has visibly different parts.

Step1: Identify substance A (based on magnetism)

Neodymium powder (\(Nd\)) is “highly magnetic” (from the table). So if \(A\) is magnetic, \(A=\text{Neodymium powder}\)

Step2: Identify substance B (based on solubility in water)

Ammonium chloride (\(NH_4Cl\)) is “soluble in water” (from the table). So \(B = \text{Ammonium chloride}\)

Step3: Identify substance C (based on solubility in water at different temperatures)

Benzoic acid (\(C_7H_6O_2\)) has solubility in water that changes with temperature (\(insoluble\) in water below \(45^{\circ}C\), \(soluble\) in water above \(45^{\circ}C\)). So \(C=\text{Benzoic acid}\)

Step4: Identify substance D (by elimination)

By elimination, \(D=\text{Lead (II) chloride}\) (\(PbCl_2\))

Answer:

A. heterogeneous; heterogeneous

16.