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3. 2.3g of a metal halide of formula type MX (M = metal, X = halide) was dissolved in water and reacted

with excess silver nitrate. 5.63 g of a white silver halide precipitate was produced.
a) Identify the halide ion present in the salt MX.
b) Calculate the number of moles of silver halide precipitate produced.
c) Deduce the number of moles of halide ion in the halide salt MX and calculate the mass of halide
present in the 2.3g sample.
d) Calculate the percentage mass of halide in the halide salt MX.
e) Deduce the number of moles of metal M present in the halide salt MX.
f) Calculate the mass of metal M present in the halide salt MX.
g) Calculate the molar mass of the metal M present in the halide salt and hence identify the metal.

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User Vianmixt
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1 Answer

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a) The white precipitate formed in the reaction is silver halide (AgX), where X is the halide ion present in the salt MX.

b) The number of moles of silver halide precipitate produced can be calculated as follows:

moles of AgX = mass / molar mass = 5.63 g / (107.87 g/mol) = 0.052 moles

c) From the balanced chemical equation for the reaction, we know that 1 mole of MX reacts with 1 mole of AgNO3 to form 1 mole of AgX. Therefore, the number of moles of halide ion in the MX sample is also 0.052 moles.

mass of halide = moles of halide ion x molar mass of halide ion

Since we don't know which halide ion is present, we can calculate the masses for each possible option:

For chloride (Cl-): mass of halide = 0.052 moles x 35.45 g/mol = 1.84 g

For bromide (Br-): mass of halide = 0.052 moles x 79.90 g/mol = 4.16 g

For iodide (I-): mass of halide = 0.052 moles x 126.90 g/mol = 6.60 g

Therefore, the mass of halide present in the 2.3 g sample depends on the identity of the halide ion.

d) The percentage mass of halide in the MX sample can be calculated as follows:

% halide = (mass of halide / mass of MX) x 100%

Since we don't know the mass of MX, we cannot calculate this value.

e) The number of moles of metal M present in the halide salt MX can be calculated by subtracting the number of moles of halide ion from the total number of moles in the sample:

moles of metal M = total moles - moles of halide ion

total moles = mass / molar mass = 2.3 g / molar mass of MX

We cannot calculate the molar mass of MX without knowing the identity of the metal and halide ion.

f) The mass of metal M present in the halide salt MX can be calculated by multiplying the number of moles of metal M by its molar mass. However, we do not have enough information to calculate this value.

g) We cannot calculate the molar mass of the metal M present in the halide salt without knowing the identity of the metal and halide ion.

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User Pioto
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