Suppose that a 10-mL sample of a solution is to be tested for Cl- ion by addition of 1 drop (0.2mL ) of 0.15 M AgNO3 .
What is the minimum number of grams of Cl- that must be present in order for AgCl(s) to form?
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To determine the minimum number of grams of Cl- that must be present for AgCl(s) to form, we need to calculate the amount of AgNO3 required for the reaction and then use stoichiometry to find the amount of Cl- corresponding to that amount of AgNO3.
Step 1: Calculate the number of moles of AgNO3 used:
Given:
Volume of AgNO3 = 0.2 mL = 0.2/1000 L = 0.0002 L
Concentration of AgNO3 = 0.15 M
Number of moles of AgNO3 = Concentration × Volume
= 0.15 M × 0.0002 L
= 0.00003 mol
Step 2: Use stoichiometry to find the molar ratio of Cl- to AgNO3:
From the balanced chemical equation for the reaction between AgNO3 and Cl-:
AgNO3 + Cl- -> AgCl(s) + NO3-
From the equation, we can see that the ratio of moles of Cl- to moles of AgNO3 is 1:1.
Step 3: Calculate the number of moles of Cl- corresponding to the moles of AgNO3:
Number of moles of Cl- = 0.00003 mol
Step 4: Calculate the mass of Cl-:
To calculate the mass of Cl-, we need to know the molar mass of Cl-, which is approximately 35.5 g/mol.
Mass of Cl- = Number of moles × Molar mass
= 0.00003 mol × 35.5 g/mol
= 0.00105 g
Therefore, the minimum number of grams of Cl- that must be present in order for AgCl(s) to form is approximately 0.00105 grams.
To find the minimum number of grams of Cl- required for AgCl(s) to form, we can use the concept of stoichiometry and the balanced chemical equation for the reaction between AgNO3 and Cl-.
The balanced chemical equation for the reaction is:
AgNO3 + Cl- -> AgCl + NO3-
From the equation, we can see that 1 mole of AgNO3 reacts with 1 mole of Cl- to form 1 mole of AgCl. The molar mass of Cl- is approximately 35.45 g/mol.
Now, let's calculate the amount of AgNO3 used in this reaction:
0.2 mL of 0.15 M AgNO3 = (0.2/1000) L x 0.15 mol/L = 0.03 x 0.15 mol = 0.0045 mol AgNO3
Since the stoichiometry of the reaction is 1:1 between AgNO3 and Cl-, we need the same number of moles of Cl- for the reaction. Therefore, we can say that 0.0045 moles of Cl- are required for AgCl to form.
To find the minimum mass of Cl-, we can use the molar mass of Cl- (35.45 g/mol):
Mass of Cl- = moles of Cl- x molar mass of Cl-
= 0.0045 mol x 35.45 g/mol
= 0.15953 g
Therefore, the minimum number of grams of Cl- that must be present for AgCl(s) to form is approximately 0.15953 grams.