Section 5.4 pg

 Standard Solution – solutions with precisely known concentrations  Used in chemical analysis and to precisely control chemical reactions  Precision equipment is required to measure mass of solute (electronic balances) and volume of solution (volumetric flask)

 Volumetric Flask – glass flask with a long, narrow neck used to prepare a highly precise volume of solution  Precise to ±0.16 mL at 20°C (i.e mL volumetric flask is uncertain to less than 0.2 mL )  Graduated Cylinders – glass cylinder with regular markings used to measure a fairly precise volume of liquid or solution  Erlenmeyer Flask – glass cone-shaped flask with a large flat bottom used to mix a solution sample during titration; markings only approximate volume  Beaker – glass wide-body cylinder with regular markings used for transferring and storing solutions or solids, and containing reactions; markings are only approximate volumes precise to only ±5 mL

 Use conversion factors to determine the values for both the amount in moles and the mass of solid required.  Because you are working with one substance, you do not need a balanced equation (No need for a mol ratio)  Volume of the solution and its molar concentration are needed.  Example: To prepare 250.0mL of mol/L solution of sodium carbonate, the mass needed is: L x mol x g = 2.65 g 1 L 1 mol

 Pg. 216 #1, 2, and 4(a)

 Standard solutions – a solution with a concentration that is known with considerable certainty; a solution of accurate concentration  Read over your procedure given  Nelson Master 30

 Dilution – decreasing the concentration of a solution  Usually accomplished by adding more solvent  The number of moles of solute DOES NOT change when a solution is diluted (# of moles before = # of moles after)  Dilution is especially important in manipulating the concentration of solutions in chemistry for better control of reactions  Concentrated solution reactions can be too violent to be safe and/or too fast to observe  Stock Solution – the initial starting solution from which samples are taken for a dilution; usually very high concentrations

More Volumetric Glassware :  Pipet – glass tube used to deliver very precise, small volumes of solution; requires a pipet bulb to fill the pipet Two Types: a)Graduated Pipet – graduation marks every 1% of the volume (i.e. 10 ml would be marked every 0.1 mL) -Can transfer any volume from 1 – 100% -Precise to ±0.1 mL b)Volumetric Pipet – bulge in the middle with one graduation marking -“TD” inscription means “to deliver” a certain volume -Transfers one specific volume (1 mL, 10 mL); precise ±0.02 mL ( most precise piece of glassware)

 We know that the number of moles does not change when diluting a solution, but the concentration and volume will. So we will use the dilution formula: C 1 V 1 = C 2 V 2  To use the dilution formula, you must make sure the units are consistent for both the c and v (i.e. both in mL or both in L)  Example: How would you prepare 100 mL of 0.40 mol/L MgSO 4(aq) from a solution of 2.0 mol/l MgSO 4(aq) C 1 V 1 = C 2 V 2 (2.0mol/L) (V 1 ) = (0.40mol/L) (100mL) V 1 = 20 mL

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 Standard solutions – a solution with a concentration that is known with considerable certainty; a solution of accurate concentration  Read over your procedure  Nelson Master 30  Practice PipettingPipetting