chem1013-quiz 5: end of chapter 4 and chapter 5

What is theoretical yield?

amount of product that can be made based on the limiting reagent

What is limiting reagent?

reactant that is completely consumed; limits product amount

What is excess reagent?

reactant still left over after reaction is complete

What is actual yield?

amount of product actually produced

What is the percent yield formula?

Percent yield = (actual yield / theoretical yield) x 100% 

What are the steps to find theoretical yield, limiting reactant, excess reactant(s), and percent yield?

1. convert reactants to grams of the product asked in the equation

2. theoretical yield= grams of product formed based on limiting reactant

3. Limiting reactant= least amount of grams of product

4. Excess reactant= the reactant that remains after the reaction in complete

5. Find the percent yield by:

   1. dividing actual yield (usually given in problem) by theoretical yield calculated

   2. multiply by 100%

In this experiment, 28.6kg of C reacted with 88.2kg of TiO2, and 42.8kg of Ti was produced. What is the theoretical yield (in kg) of Ti, and what is the percent yield for this reaction? Also, identify the limiting and excess reagents.

To determine the theoretical yield of titanium (Ti), convert the masses of carbon (C) and titanium dioxide (TiO2) to Ti using stoichiometry based on the balanced reaction equation. The limiting reactant will be the one that produces the least amount of Ti, while the excess reagent is the one that remains after the reaction is complete. Percent yield is calculated by dividing the actual yield (42.8 kg) by the theoretical yield and multiplying by 100%.

What is a solution?

homogeneous, uniform mixture of 2 substances

What is a solvent?

majority component (often water)

What is a solute?

minority component

What is an aqueous solution?

solvent is water

What is a dilute solution?

small amount of solute relative to the solvent

What is a concentrated solution?

large amount solute relative to solvent

What can solution concentration be expressed as?

Molarity (M)

What is the formula for molarity (M)?

M = moles of solute / liters of solution

What is the molarity of a solution with 25.5 g KBr dissolved in enough water to make 1.75 L of solution?

To find the molarity, first calculate the moles of KBr by using its molar mass (119.00 g/mol). Molarity (M) is then calculated as moles of solute divided by the volume of solution in liters. Therefore, M = (25.5 g / 119.00 g/mol) / 1.75 L = 0.123 M.

What volume (in mL) of a 0.155 M KCl contains 2.55 g KCl?

To determine the volume in milliliters, first calculate the moles of KCl using its molar mass (74.55 g/mol). Then, apply the molarity formula (M = moles of solute / liters of solution) to find the volume in liters, and convert to milliliters. Thus, volume = (2.55 g / 74.55 g/mol) / 0.155 M = 220 mL.

What are stock solutions?

concentrated forms of solutions

How do we use stock solutions for our experiments?

we add solvent (usually water) to increase the volume and decrease the concentration (amount of solute stays the same); simple, we are diluting the stock solution to the desired concentration for use in experiments.

What equation do we use for dilutions, and what are the rules for this formula?

M₁V₁ = M₂V₂
M₁ = initial concentration (stock)

V₁ = initital volume

M₂ = final concentration

V₂ = final volume

• volume units must match

• concentration units must match

A lab procedure calls for 3.00 L of a 0.5 M CaCl2 solution. How should we prep this solution from a 10.0 M stock solution?

To prepare 3.00 L of a 0.5 M CaCl₂ solution from a 10.0 M stock solution, use the dilution formula M₁V₁ = M₂V₂. Calculate V₁ as follows: V₁ = (M₂V₂) / M₁. = (0.5 M)(3.00 L) / 10.0 M = 0.150 L (150 mL) of stock solution.

What is the concentration of a solution prepared by diluting 56.6 mL of a 2.25 M stock solution with enough water to make 1.05 L of solution?

To find the concentration, use the dilution formula M₁V₁ = M₂V₂. Here, M₁ = 2.25 M, V₁ = 56.6 mL (0.0566 L), and V₂ = 1.05 L. Solving for M₂, we find M₂ = (M₁V₁)/V₂ = (2.25 M)(0.0566 L)/(1.05 L) = 0.121 M.

What can we calculate with the volume and concentration of a reactant or product?

its number of moles— using the formula: moles = concentration × volume.
* to convert between species, we use molar ratios from the equation