What are the molarity and the normality of a solution made by dissolving 5.0 g of Ca(OH) 2 in enough water to make 500.0 mL of solution?

Hello. In this problem, we are asked to calculate the concentration of a solution prepared by dissolving 10.2 g of gram hydroxide in water to make a 350 mL solution and to report the concentration in molar and normality beginning with molar molar is represented shorthand as capital M is defined as molds of solute per liter of solution. In this problem, we are given the mass of the solute. We have 10.2 g of barium hydroxide per milliliters of solution. We'll convert our via solution from milit two liters. 1000 mL of solution is equal to one liter of solution. And we will convert the mass Ofri hydroxide to mori hydroxide using its molar mass. One mole of barium hydroxide has a mass of 171.34 g. Our mass of barium hydroxide cancels and ml of solution cancels. So this works out to 0.170 moles of barium hydroxide Per liter of solution. We can express this as 0.170 Moeller vari hydroxide. Next, we're asked to find the normality normality can be represented shorthand. As capital N, it is defined as the equivalence of base per liter of solution, one equivalent of base Equal to one mole of hydroxid ions. Vari hydroxide will dissociate in a solution to form be minds And two moles of hydroxide ions. So for every one mole of barium hydroxide, we have two moles of hydroxid ions. So that means that we have two equivalents a base for every mole of vari hydroxide can find the normality by taking our equivalence of base per mole of our base times the polarity of the solution. So in this case, we have two equivalents your base for every mole of vari hydroxide. And our concentration and similarity is 0. moles of barium hydroxide per liter of solution are moles of barium hydroxide cancels. And this works out to 0.3, equivalents per leader, Which we can write as .340 normal. Thanks for watching. Hope this helps.

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10. Acids and Bases

Acid-Base Equivalents

GOB Chemistry

10. Acids and Bases

Acid-Base Equivalents

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3:30 minutes

Problem 90

Textbook Question

What are the molarity and the normality of a solution made by dissolving 5.0 g of Ca(OH)₂ in enough water to make 500.0 mL of solution?

Verified step by step guidance

Step 1: Calculate the molar mass of calcium hydroxide (Ca(OH)₂). The molar mass is determined by summing the atomic masses of all atoms in the compound: Ca = 40.08 g/mol, O = 16.00 g/mol, H = 1.008 g/mol. Therefore, the molar mass of Ca(OH)₂ is 40.08 + (2 × (16.00 + 1.008)) g/mol.

Step 2: Convert the given mass of Ca(OH)₂ (5.0 g) into moles using the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \). Substitute the values for mass and molar mass to find the number of moles of Ca(OH)₂.

Step 3: Calculate the molarity (M) of the solution using the formula: \( M = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \). Convert the given volume of the solution (500.0 mL) into liters by dividing by 1000, then substitute the moles of Ca(OH)₂ and the volume in liters into the formula.

Step 4: Determine the normality (N) of the solution. For Ca(OH)₂, each molecule provides 2 hydroxide ions (OH⁻), so the equivalent factor is 2. Use the formula: \( N = M \times \text{equivalent factor} \). Multiply the molarity by the equivalent factor to find the normality.

Step 5: Summarize the results. The molarity represents the concentration of Ca(OH)₂ in moles per liter, while the normality accounts for the number of equivalents of hydroxide ions per liter of solution.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is calculated using the formula M = moles of solute / liters of solution. In this case, to find the molarity of the Ca(OH)₂ solution, one must first convert the mass of the solute into moles using its molar mass and then divide by the volume of the solution in liters.

Normality

Normality is another measure of concentration that reflects the number of equivalents of a solute per liter of solution. It is particularly useful in acid-base reactions and redox reactions. For Ca(OH)₂, which can donate two hydroxide ions (OH⁻) per formula unit, the normality can be calculated by multiplying the molarity by the number of equivalents, which is determined by the number of reactive species in the solution.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting between grams and moles when calculating concentrations. For Ca(OH)₂, the molar mass is calculated by summing the atomic masses of calcium (Ca), oxygen (O), and hydrogen (H) in the compound, which is necessary to determine how many moles are present in the given mass of the solute.

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