Solutions

Question of the Day What are the 3 states of matter? Draw what each looks like in terms of how close or far apart the particles of matter are positioned

Review: States of Matter

What about plasma? (Enrichment)

Review: Mixtures A mixture is a substance made up of two or more substances which are physically combined. A mixture can be heterogeneous or homogeneous Examples:

Review: Heterogeneous Mixtures A heterogeneous mixture is a mixture where we can distinguish (see or identify) the different parts that make up the total mixture

Review: Homogeneous Mixture (Solutions) A homogeneous mixture is a mixture where we cannot distinguish (see or identify) the different parts that make up the total mixture. A homogenous mixture is also called a solution.

Solutions A solution is a homogeneous mixture A solution contains a solute and a solvent Solute: what is being dissolved Solvent: what is present in the greatest amount

Dissolution looks like…

Comparing Solutions Suppose I add some sugar into 3 different glasses… Which one will taste the sweetest? Why?

Comparing Solutions Continued… Now suppose each glass has 1 teaspoon of sugar but different amounts of water Which is the sweetest?

Concentration Concentration = 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡 𝑐 ( 𝑔 𝐿 )= 𝑚 (𝑔) 𝑣 (𝐿) for the sugar/water example But a concentration can also be liquid-liquid, gas-liquid, etc. 𝑐 ( 𝑚𝐿 𝐿 )= 𝑣 (𝑚𝐿) 𝑣 (𝐿) for food colouring/water 𝑐 ( 𝐿 𝐿 )= 𝑣 (𝐿) 𝑣 (𝐿) for the oxygen gas in air (nitrogen gas)

Dimensional Analysis AKA converting between different values 3 500mL in L? 125 450 sec in weeks? 15 kg of water in L?

Concentration Example Which will taste more sugary?

Concentration % Notation Concentrations are sometimes given as a percentage When no other information is given, it is implied that the percentage means: % = # 𝑜𝑓 𝑔𝑟𝑎𝑚𝑠 𝑝𝑒𝑟 100 𝑚𝑙 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡 E.g. 25% = 25 𝑔 100 𝑚𝐿 In other cases, you may encounter % mass/mass % volume/volume

Comparing Concentrations Example 2 Rank the following concentrations from lowest to highest 50g/1250ml 75% mass by volume 0.5kg/1.5L

Concentrations Example 3 Suppose I add 250 ml of orange juice to 450 ml of grapefruit juice. What is the total concentration of orange juice?

Making Iced Tea Why do we start with hot tea?

Solubility The solubility of a substance is a fundamental property. It is a measure of how much solute can be dissolved into a liquid (usually water) For a solid solute, increasing the temperature of the solution will increase its solubility However, for a dissolved gas, increased temperature decreases its solubility E.g. Soda will go flat faster if it’s warm versus when it is cold Due to particle agitation allowing for gas to escape If a substance cannot be dissolved, it is insoluble

Dilutions Sometimes, a solution can be too concentrated. We reduce the overall concentration of a solution by diluting it The usual way to achieve this is to simply add more solvent Sometimes, we can take a sample (aliquot) and then add more solvent

𝐶 1 𝑉 1 = 𝐶 2 𝑉 2 Formula For Dilutions Where: 𝐶 1 𝑉 1 = 𝐶 2 𝑉 2 Where: C1 = concentration of original (initial) solution C2 = concentration of final solution V1 = initial volume V2 = final total solution Remember the formula, but especially know how to use and apply it Technically this formula applies for making something more concentrated too

Dilution Example Suppose I have 5g of salt in 100mL of water. If I dilute the solution to 125ml, what will the new concentration be?

Dilution Example 2 If I have a 500ml of a 25% sugar solution, how much water will I need to add in order to get a 15% sugar solution?

Dilution Example 3 After dilution, my iced tea mixture now has a concentration of 36g/L. Suppose my initial volume was 250 ml and my final volume was 1200 ml, what was the initial concentration?

Last Word When I am dissolving a solute or diluting a solution, what kind of change is this?