Question

Give the oxidation number for the species or the indicated atom in the following:

Cs in Cs2O

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Calculate the mass of KI in grams required to prepare 5.00 × 102 mL of a 3.0 M solution

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A sample of 0.3151 g of an ionic compound containing the bromide ion (Br−) is dissolved in water and treated with an excess of AgNO3. If the mass of the AgBr precipitate that forms is 0.7199 g, what is the percent by mass of Br in the original compound?

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A sample of 0.7960 g of an unknown compound containing barium ions (Ba2+) is dissolved in water and treated with an excess of Na2SO4. If the mass of the BaSO4 precipitate formed is 0.7651 g, what is the percent by mass of Ba in the original unknown compound?

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How many grams of NaCl are required to precipitate most of the Ag+ ions from 2.50 × 102 mL of 0.0467 M AgNO3 solution?

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The concentration of Cu2+ ions in the water (which also contains sulfate ions) discharged from a certain industrial plant is determined by adding excess sodium sulfide (Na2S) solution to 0.600 L of the water. The molecular equation is

Na2S(aq) + CuSO4(aq) → Na2SO4(aq) + CuS(s)

Calculate the molar concentration of Cu2+ in the water sample if 0.0183 g of solid CuS is formed.

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How many grams of KHP are needed to neutralize 75.47 mL of a 0.1041 M NaOH solution?

(molar mass of KHP = 204.2 g/mol)

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Calculate the volume of a 1.420 M NaOH solution required to titrate 36.75 mL of a 1.500 M H3PO4 solution.

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Answer 1

1.Sol :-

Oxidation number of Cs in Cs₂O = 2 x Oxidation number of Cs + 1 x Oxidation number of O

0 = 2 x Oxidation number of Cs + 1 (-2)

2 x Oxidation number of Cs = + 2

Oxidation number of Cs = +2/2 = +1

Oxidation number of Cs = +1

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2.Sol :- As, Molarity = Number of moles/ Volume of solution in L

So,

Number of moles of KI = Molarity x Volume of solution in L

= 3.0 M x 0.500 L

= 1.50 mol

Also, Number of moles = Mass in g / Gram molar mass

So,

Mass of KI in g = Number of moles of KI x Gram molar mass of KI

= 1.50 mol x 166.0028 g/mol

= 2.49 x 10² g

Hence, Mass of KI required = 2.49 x 10² g