Gravimetric Analysis: Conversions and Calculations

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What is the purpose of adding Mg2+ and aqueous NH3 in the procedure to determine the percentage of P in a sample of commercial phosphate detergent?

To destroy the organic matter in the sample
To convert the residue to Mg2P2O7
To precipitate the phosphate as MgNH4PO4.6H2O (correct)
To convert the P to H3PO4

What is the mass of CaO per gram of CaC2O4 precipitate?

100 g/mol / 40.078 g/mol
40.078 g/mol / 100 g/mol
100 g/mol / 56.077 g/mol
56.077 g/mol / 100 g/mol (correct)

In the determination of Ca in a natural water sample, what is the purpose of igniting the CaC2O4 precipitate in a crucible?

To convert the CaC2O4 to CaO (correct)
To destroy the organic matter in the sample
To determine the mass of the crucible
To filter and wash the precipitate

What is the gravimetric factor (GF) for the precipitation of AgCl?

Cl/AgCl (A) Signup and view all the answers

What is the percentage of P in a sample of commercial phosphate detergent, given that 0.2161 g of Mg2P2O7 is obtained from 0.3516 g of the sample?

17.11 %P (D) Signup and view all the answers

What is the concentration of Ca in a natural water sample, given that 26.7134 g of CaO is obtained from 200.0 mL of the sample?

4.045 x 10^-4 g/mL (B) Signup and view all the answers

What is the primary analytical parameter in the classical method of determining carbon and hydrogen in organic compounds?

The change in mass of the combustion products (B) Signup and view all the answers

What is the purpose of adding an excess of paraperiodic acid in the precipitation reaction of mercury?

To ensure complete precipitation of mercury (D) Signup and view all the answers

What is the product of the reaction between ammoniacal nitrogen and chloroplatinic acid?

Slightly soluble ammonium chloroplatinate (A) Signup and view all the answers

What is the percentage of Hg2Cl2 in the sample if 0.5718 g of precipitate is recovered from a 1.0451-g sample?

54.81 % (C) Signup and view all the answers

What is the purpose of igniting the precipitate of ammonium chloroplatinate in the determination of ammoniacal nitrogen?

To produce metallic platinum and gaseous products (B) Signup and view all the answers

What is the percentage of ammonia in a sample if 0.2115 g of sample produces 0.4693 g of platinum?

45.79 % (B) Signup and view all the answers

If 1.1682 g of precipitate were obtained from a 0.2711-g sample, what is the percent P in the sample?

7.113% (A) Signup and view all the answers

If a 1.52-g sample yields Mn3O4 weighing 0.126 g, what would be the percent Mn2O3 in the sample?

8.58% (A) Signup and view all the answers

A 1.1324-g sample of a magnetite ore was dissolved in concentrated HCl to give a solution. What is the percent Fe in the sample?

33.32% (B) Signup and view all the answers

What weight of pyrite ore must be taken for analysis so that the weight of BaSO4 precipitate obtained will be equal to one-half of the percent S in the sample?

6.870 g (C) Signup and view all the answers

What is the formula of the compound obtained after the addition of NH3 to the solution of magnetite ore?

Fe2O3.xH2O (A) Signup and view all the answers

What is the formula of the compound used to determine the percent P in the sample?

(NH4)3PO4.12MoO3 (B) Signup and view all the answers