Lab # 8

Key Terms Homogeneous Vs. Heterogeneous Saturated Vs. Unsaturated Solute Vs. Solvent Moles Vs Molarity Percent Weight and Percent Volume

Solutions can be: Saturated – holding all it can hold at that temp. Unsaturated- not living up to it potential Supersaturated – overachiever holding more then it is supposed to hold. These are very unstable.

Homogeneous Vs. Heterogeneous Homogeneous – the same all through. Example plain Vanilla ice cream Not Breyers Heterogeneous – not the same. Any other type of ice cream with stuff init. Applies to types of solutions.

Saturated Solutions A solution will hold a specific amount of a salt at a specific temperature. Generally as temperature increases the amount of salt a solution can hold will increase. See chart on the back of the periodic table. All based off a 100g of water.

Saturated Vs. Unsaturated If a solution contains less salt then it can hold AT A SPECIFIC TEMPERATURE then it is unsaturated. Where the temperature line and the amount of salt in the solution line intersect, this is the amount of salt it will take to saturate the solution at that specific temp.

Solute Vs. Solvent Solvent - That which dissolves something else. Ex water is the universal solvent. Solute – The part that is being dissolved. –Ex ice tea mix in a glass of water. –Table salt in water.

moles Vs. Molarity moles – contain a specific number of parts. We use this number of moles to determine reactions. Molarity is a concentration. This is a specific number of moles in 1 L of solution. Always based off of 1 L of solution

Example # 1 Given.10moles of NaCl and 1 liter of solution what is the Molarity? Always assume 1 L of solution unless told otherwise.

Example # 2 Given: We have a 5M solution of HCl and we used 5 mL how many moles did we use? Use the Molarity formula and solve for the one not given. We did not use the entire liter of solution we only used 5 mL or 0.005L The solution is still based off of 1 L even if we did not use the whole liter.

Given 5M HCl solution and we used 5 mL how many moles did we use?

Percent Weight and Percent Volume Always percent part over whole X 100 How many grams of NaHCO 3 is in a 10% solution with a total weight of 55g ?

Table A Observe determine physical states of the samples. Part # 2 We will prepare a 2M NaCl solution. If we making 1 L how many moles of NaCl would we need? 2 moles.

We will prepare 100 mL. not 1000 mL (1 L) 100 mL. is 1/10 of a liter So we will only need 1/10 of the NaCl. If 1 mole of NaCl = 110g then 1/10 of a mole =? 11.7g NaCl needed

Part #4 Obtain two 2.0g and one 1.0g samples of KNO 3. Place the 1 g sample in a large test tube with 5 mL. of H 2 O Place test tube in an ice bath and stir until dissolved. Determine the temp when the crystals dissolve.

If the crystals do not dissolve apply mild heat and stir. When the last crystal dissolves record the temperature. Add 2 grams of salt to your test tube and mix. Place Test tube in a hot water bath. Determine the temp when the last crystal dissolves. Add the last 2 gram sample of salt and repeat procedures. Graph results on page 60

Due Next Week: Complete lab: pgs57-59 ignore part # 3 Complete homework and exercise pgs 61-62