Types of Solution
This is the term for the substance being dissolved in a solution.
Solute
A solution with very little solute relative to solvent is described as this.
Dilute
When you dilute a solution by adding water, this quantity of solute stays the same.
moles or grams
Name the three methods for preparing a solution covered in this unit.
From a solid, from a stock solution, through serial dilution
Draw the ion-dipole interactions that form when NaCl dissolves in water. Your diagram should show the partial charges on water and the full charges on the ions.
Diagram should show: water molecules orienting with their δ⁻ oxygen toward Na⁺ ions, and their δ⁺ hydrogens toward Cl⁻ ions; Na⁺ and Cl⁻ shown as separated ions surrounded by water molecules
State the formula for molarity and identify the units of each variable.
M = n/V; M in mol/L, n in mol, V in L
State the dilution equation and explain what each variable represents.
M₁V₁ = M₂V₂; M₁/V₁ = initial molarity/volume; M₂/V₂ = final molarity/volume
When preparing a solution from a solid, this piece of glassware is used to ensure the final volume is measured accurately and precisely.
Volumetric flask
Soapy water is NOT considered a true solution. Of the following — NaCl(aq), HCl(aq), sugar water — name one and identify what type of solute it contains (ionic or polar covalent molecular).
Also, Which is an acid?
Answer: NaCl(aq) → ionic; HCl(aq) → polar covalent molecular (that reacts with water to give ions / acid); sugar water → polar covalent molecular
A student dissolves 0.58 mol of NaOH into enough water to make 156. mL of solution. What is the molarity of the solution?
3.72 M
How many mL of a 6.15 M HCl stock solution are needed to prepare 550. mL of 0.340 M HCl? How much water do you need to add to it? (note: for acids, you add acid TO water - and slowly!)
V₁ = 30.4 mL
Water: 519.6 mL
A student performs a serial dilution starting from a 1.0 M stock solution, doing 4 successive 10× dilutions. What is the final concentration, and why is serial dilution preferred over a single dilution for reaching such low concentrations?
Final concentration = 1.0 × 10⁻⁴ M; serial dilution is preferred because pipetting very small volumes accurately in a single dilution is impractical — serial dilution reduces error by using manageable volumes at each step
HCl dissolves in water to produce H⁺ and Cl⁻ ions. What is the term for any substance that dissolves in water to give ions, and what property does this give the solution?
Electrolyte; it conducts electricity
A student needs 150. mL of a 0.800 M MgCl2 solution. How many grams of MgCl2 are needed?
11.4 g
A student has 45.5 mL of a 3.25 M NaOH solution. They add water until the final volume is 275. mL. What is the final concentration?
= 0.538 M
Name one error for each method of solution making that a student could make to impact the accuracy and precision of their solution.
- From a solid
- From stock solution
- Through serial dilution
AMV