Answer:
The molarity of a solution is 2.5 M
Explanation:
Molarity is a concentration unit that describes how much of a solution is dissolved in solution.
Molarity of a solution can found by using the formula,
Molarity (M) = (moles of solute)/(Liters of Solution).
Given, mass of Sodium = 114.95 grams.
Volume of water = 2 L.
Here, Sodium is solute as it is dissolved in water, which is the solvent.
Moles of Sodium(solute) can be found by using the formula,
Number of Moles = mass/Molecular weight.
mass of Sodium = 114.95 grams.
Molecular weight = 22.989 grams
Number of Moles of Sodium(solute) =114.95/22.989 = 5.
Substituting the values in the formula, we get,
M = 5/2 = 2.5 M
Answer:
The answer is 0.0698 M
Explanation:
The concentration was prepared by a serial dilution method.
The formula for the preparation I M1V1 = M2V2
M1= the concentration of the stock solution = 0.171 M
V1= volume of the stock solution taken = 200 mL
M2 = the concentration produced
V2 = the volume of the solution produced = 940 mL
Substitute these values in the formula
0.171 × 200 = 490 × M2
34.2 = 490 × M2
Make M2 the subject of the formula
M2 = 34.2/490
M2 = 0.069795
M2 = 0.0698 M ( 3 s.f)
The concentration of the Chemist's working solution to 3 significant figures is 0.0698M
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From the periodic table:
mass of oxygen = 16 grams
mass of calcium = 40 grams
mass of carbon = 12 grams
mass of CaCO3 = 40 + 12 + 3(16) = 100 grams
Therefore, each 100 grams of CaCO3 contains 3 moles of oxygen
To know the number of oxygen moles in 25.45 grams, we will simply do cross multiplication as follows:
number of oxygen moles = (25.45 x 3) / 100 = 0.7636