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SOLUTIONS. Chapter 7 Beg Che m. SOLUTION. Is a s_______ dissolved in a s_________ We can work out the concentration of a solution A saturated solution is one that can dissolve no more solute at a given temperature. MAKING RARO. A packet of raro weighs 95g
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SOLUTIONS Chapter 7 Beg Chem
SOLUTION • Is a s_______ dissolved in a s_________ • We can work out the concentration of a solution • A saturated solution is one that can dissolve no more solute at a given temperature
MAKING RARO A packet of raro weighs 95g • If you dissolve in 1 litre of water what will the concentration be in g L-1 • You leave it out in the sun (in Raro) and half the water evaporates, what is the new concentration • You go on camp, they use 6 packets for a 15L container of water
CONCENTRATION • Example Seawater has 35g L-1 of NaCl, how much NaCl would you get if you evaporated 80mL of seawater
PERCENTAGE SOLUTION • How much does 1mL of water weigh? • 1mL = 1g • 1000mL = 1000g • A 10% aqueous solution of NaCl means 10g/___g or 10g/____mL • (w/v) = weight/volume • (w/w) = weight/weight • In aqueous solutions these 2 are interchangeable as 1mL water weighs 1g
EXERCISE • Act 7A Concentration by Mass (p88)
MOLES PER LITRE • Only difference – change mass to moles • We use a new formula New formula Old formula
STARTER • You dissolve 0.5mol of NaCl in 250mL of water, work out the concentration in mol L-1 • You want to make 300ml of a 0.2mol L-1 solution of copper sulfate. How many moles fo you need • What volume of water is need to make a 0.1mol L-1 solution with 0.05mol of PbBr2
EXPERIMENT • Prac 7.1
STANDARD SOLUTION • A standard solution has a known concentration • Remember the 2 important formulas
EXERCISE • Read through examples 7.5 and 7.6 (p89) • Act 7C p94-95