Respuesta :
Calcium content as a mass percentage in milk is 0.106%.
To calculate the number of moles, we use the equation shown below:
Given mass ÷ Molar mass = number of moles
Given that 0.429 g of calcium oxalate is present
Calcium oxalate has a molar mass of 128.1 g/mol.
By changing the values,
A number of moles = 0.429 ÷ 128.1 g/mol = 0.0033 mol
The given chemical equation follows:
[tex]Na_2C_2O_4(aq.) + Ca^{2+}(aq.)[/tex] → [tex]CaC_2O_4(s) + 2Na^{+}(aq.)[/tex]
Overabundant sodium oxalate is found. Therefore, it is regarded as an excess reagent. Additionally, calcium ion is a limiting reactant since it restricts the product's ability to form.
Using the reaction's stoichiometry:
From 1 mole of calcium ion, 1 mole of calcium oxalate is created.
Thus, produces 0.0033 moles of calcium oxalate.
(1 ÷ 1) × 0.0033 = 0.0033 mol of calcium ions.
Using equation 1, we can now calculate the mass of calcium ions and obtain:
Calcium ions in moles equal 0.0033 moles.
Calcium ions have a molar mass of 40 g/mol.
Equation 1 is solved for the following values:
0.0033 mol = Mass of calcium ions ÷ 40 g/mol
Mass of calcium ions = 0.0033 mol × 40 g/mol = 1.132
We employ the following equation to get the mass proportion of calcium ions from milk:
The mass percent of calcium ions = (Mass of calcium ions ÷ Mass of milk) × 100
Milk weighs 125 g.
Calcium ions' mass is 0.132 g.
By entering data into the aforementioned equation, we obtain the following,
The mass percent of calcium ions = (0.132g ÷ 125g) × 100 = 0.106%
As a result, milk has a mass percent of calcium of 0.106%.
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The question is -
The amount of calcium present in milk can be determined through gravimetric analysis by adding oxalate to a sample and measuring the mass of calcium oxalate precipitated. What is the mass percent of the calcium in milk if 0.429 g of calcium oxalate, CaC2O4, forms in a 125-g sample of milk when excess aqueous sodium oxalate is added?
Na2C2O4 (aq) + Ca2+ (aq) → CaC2O4 (s) + 2 Na+ (aq)
