General Chemistry PDF - Solution, Concentration, and Percentage

# General Chemistry ## Solution, Concentration and Percentage - **Solution:** is a mixture of one or more solutes dissolved in a solvent. - **Solvent:** the substance in which a solute dissolves to produce a homogeneous mixture. - **Solute:** the substance that dissolves in a solvent to produce a...

# General Chemistry ## Solution, Concentration and Percentage - **Solution:** is a mixture of one or more solutes dissolved in a solvent. - **Solvent:** the substance in which a solute dissolves to produce a homogeneous mixture. - **Solute:** the substance that dissolves in a solvent to produce a homogeneous mixture. - The process of a solution happens at the effects of chemical polarity, resulting in interactions. - **Concentration:** is a measure of the amount of solute in a amount of solvent. - The term "aqueous solution" is used when one of the solvents is water. ## Concentration and Percentage - **Molarity(M) =mole/volume(L)** - mole=mass/molar mass - molar mass =sum. of atomic masses - 1L=1000 ml - 1ml=1cc, 1dc=100ml - **Example:** what is the molarity of 60g of NaOH in 0.25L? - Na=23u, H=1u,O=16u. - Sol. Molar mass=23+16+1=40 g/mole - mole= 60/40 → mole=1.5 - M=1.5/0.25 → M=6 M NaOH solution - **H.W:** what's M of a solution that contains 75g of KNO3 dissolved in 0.35L of solution? - K=39u, N=14u,O=16. ## Percent (%) Concentration - **%(w/v) concentration:** mass of solute in grams contained by 100 mL solution - **%(w/w) concentration:** mass of solute in grams contained in 100 g of solution - **%(v/v) concentration:** volume of solute in mL in 100 mL solution ### How to Calculate Concentration: - **weight percent (w/w) = (weight solute/weight solution) * 100%** - **volume percent (v/v) = (volume solute/volume solution) * 100%** - **weight/volume percent (w/v) = (weight solute, g /volume solution, mL) * 100%** ### Examples: - **Example 1:** A student prepared a solution by adding H₂O to 18 ml of CH3CH2OH to give a final volume of 150 ml. What is (V/V) of ethanol? - Sol. (V/V)= (18/150) * 100% = 12% ethanol - **Example 2:** 80.0 g of salt solution contains 10.0 g of salt. What is the concentration (w/w) of the salt solution? - Sol. concentration %(w/w) = (mass of solute / mass of solution) * 100 = (10.0/80.0) * 100 = 12.5%(w/w) - **Example 3:** How much 2.0 M NaCl solution would you need to make 250 mL of 0.15 M NaCl solution? - * C₁V₁ = C2V2 - * C₁ = 2.0 mol/L - * V₁ = ? - * C₂ = 0.15 mol/L - * V₂ = 0.250 L - * V₁ = (0.15 mol/L * 0.250 L) / 2.0 mol/L = 0.0188 L = 18.8 mL - **Example 4:** How would you prepare 60.0 mL of 0.2 M HNO3 from a stock solution of 4.00 MHNO3? - * CoVo = CaVa - * Co = 4.00M - * Vo = ? - * Ca = 0.200M - * Va = 0.06 L - * Vo = (0.200M * 0.06 L) / 4.00M = 0.003 L = 3 mL - * 3 mL of acid + 57 mL of water = 60 mL of solution ## How to Calculate Concentration of a Diluted Solution A diluted solution has a lower concentration of solute due to the addition of solvent to the original solution. - **Using equation: C1 * V1 = C2 * V2** - Concentration of diluted solution: **C2 = (C1 * V1) / V2** ## Another Dilution Problem - If 32 mL stock solution of 6.5M H₂SO₄ is diluted to a volume of 500 mL what would be the resulting concentration? - CoVo = CaVa - (6.5M) * (32 mL) = Ca * (500 mL) - Ca = (6.5 M * 32 mL) / 500 mL = 0.42 M ## Problem 1: - 40 ml of 0.1 N NaOH is diluted to a final volume of 80mL. What is the normality of this diluted solution? - Solution: By using the above data we can use the below formula: - NV₁ = N₂V₂ - 40 x 0.1 = N₂ × 80 - N₂ = (40 x 0.1) / 80 = 0.05 N - So, the final concentration of the solution is 0.05 N. ## Normality - **Example:** What is the normality of a solution made by dissolving 2.50 grams of sodium hydroxide in water to make 5.00 × 10² mL of solution? - By definition, N = (equivalents solute) / (liter solution) = eq/L - Therefore, we need to find equivalents of solute and liters of solution. - Solution: m.wt. 40 eqwt= 1/n = 40 g/eq NaOH ----> Na+ + OH OH=1→ n=1 - eq = (wt/eqwt) = (2.50/40) = 0.06 eq - N = (eq/L) = (0.06/0.5) = 0.12 eq/L - V = 5.00 X 10² ml= 0.5 L - **H.W:** what is the normality of solution made by dissolving 3.7g of Ca(OH)₂ in water to make 250ml of solution? Ca=40,H=1, 0=16