Three students were asked to find the identity of the metal in a particular sulfate salt. They dissolved a 0.14 72-g sample of the salt in water and treated it with excess barium chloride, resulting in the precipitation of barium sulfate. After the precipitate had been filtered and dried, it weighed 0.2327 g.
Each student analyzed the data independently and came to different conclusions. Pat decided that the metal was titanium. Chris thought it was sodium. Randy reported that it was gallium. What formula did each student assign to the sulfate salt?
Look for information on the sulfates of gallium, sodium, and titanium in this text and reference books such as the CRC Handbook of Chemistry and Physics. What further tests would you suggest to determine which student is most likely correct?
a)
Interpretation: The formula of the sulphate salt assigned by each student has to be identified.
Concept Introduction: When two soluble solutions are mixed together, an insoluble salt formation occurs called as precipitate. These precipitates fall out of the solution and the reactions are called as precipitation reaction.
Answer to Problem 144MP
The formula of sulphate salt assigned by Pat is Titanium sulphate
The formula of sulphate salt assigned by Chris is Sodium sulphate
The formula of sulphate salt assigned by Randy is Gallium sulphate
Explanation of Solution
Given:
Record the given info
Weight of the sample =
Weight of the precipitate =
The weight of the sample and weight of the precipitate are recorded as shown above.
To calculate the moles of
Molecular mass of
Moles of
The moles of
The general equation can be given as,
The mole ratio between the unknown sulphates salt and
The moles of
To write the formula of sulphate salt assigned by Pat
Pat thinks that formula of sulphate salt is
Then the equation becomes,
There is
Assuming the molar mass of
The value of calculated molar mass of
The standard molar mass of
On comparing the standard molar mass and calculated molar mass of
The formula assigned by Pat is Titanium sulphate. The molar mass of Titanium sulphate is calculated using the weight of the sample and the moles of
To write the formula of sulphate salt assigned by Chris
Chris thinks that formula of sulphate salt is
The equation becomes,
There is
Then the molar mass of
The value of calculated molar mass of
The standard molar mass of
On comparing the standard molar mass and calculated molar mass of
The formula of sulphate salt assigned by Chris is Sodium sulphate. The molar mass of Sodium sulphate is calculated using the weight of the sample and the moles of
To write the formula of sulphate salt assigned by Randy
The formula of sulphate salt assigned by Randy is
The equation becomes,
The molar mass of
The value of calculated molar mass of
The standard molar mass of
On comparing the standard molar mass and calculated molar mass of
The formula of sulphate salt assigned by Randy is Gallium sulphate. The molar mass of Gallium sulphate is calculated using the weight of the sample and the moles of
b)
Interpretation: the most likely correct salt of sulphate has to be given.
Concept Introduction: When two soluble solutions are mixed together, an insoluble salt formation occurs called as precipitate. These precipitates fall out of the solution and the reactions are called as precipitation reaction.
Answer to Problem 144MP
The sulphate salts identified by the students are tested with aqueous Sodium hydroxide.
Explanation of Solution
To identify which salt is likely correct and what test.
By references,
Sodium sulphate (
Gallium sulphate (
Titanium sulphate occurs as green powder and has a formula of
The calculated molar mass of
Therefore, the salt is unlikely to be Titanium sulphate.
In order, to distinguish the like salt between
The sulphate salts are made to dissolve in water and later are treated with Sodium hydroxide.
Gallium (
Based on the solubility rules and the references, Gallium hydroxide is insoluble
The salt that is likely to be correct is Gallium sulphate.
The most unlike salt is to be Titanium sulphate because Titanium sulphate takes a formula of
Hence, the most likely correct salt predicted is by Randy as Gallium sulphate.
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Chapter 4 Solutions
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