Quantitative Analysis Flashcards
What is quantitative analysis
The identification of how much of a substance there is
What does hard water contain
Dissolved minerals containing Calcium and magnesium ions
What is the formula for working out concentration in G/dm-3
Conc = amount of solute in g/volume of solute in dm3
Why is more soap needed to form a lather in hard water
The calcium and magnesium ions in the water combine with the soap to make an insoluble precipitate / scum. The lather will only form once all the magnesium and calcium ions have been used up in making the scum
What is and how is limesczle formed
It is solid insoluble compound made from the dissolved magnesium or calcium compounds decompose to make insoluble compounds
What kind of water has temporary hardness
A kind of hard water that can be softened by heating to decompose the magnesium and calcium ions to form insoluble compounds
What kind of water has permanent hardness
Water that doesn’t lose its hardness when heated as the magnesium and calcium compounds don’t decompose when heated
How does an ion exchange column work
It’s a column packed with many small resin beads. On the beads are sodium ions which are weakly attached. When the hard water passes through the column, the magnesium and calcium ions swap places with the sodium ions on the beads so the water is softened
Why won’t a ion exchange column work forever and how can it be reused
Eventually all the sodium ions on the beads will have been exchanged with the magnesium or calcium ions so it no longer works, to replenish the column, a concentrated solution of NaCl is passed through the column which flushes out the calcium and magnesium ions and the sodium ions attach to the beads so the column can be used again
What is Avogadro number and its significance
It is 6.02x10^23 atoms and the mass of an substance with this many atoms is equal to its relative atomic mass in grams, e.g. Magnesiums ram is 24 so 6.02x10^23 atoms of magnesium weighs 24g
What is a mole
1 mole is also the weight of 6.02x10^23 atoms of the substance. E.g. Carbon ram is 12 so one mole of carbon is 12g of carbon
How to work out number of moles in an element and compound
Element: mass of element in grams/relative atomic mass
Compound: mass of compound in grams/relative formula mass
How do you work out mol dm-3
Number of moles of solute/volume of solution in dm-3
What is a filtrate
The solution that filters through the filter paper
How can soluble copper sulphate be made
By reacting copper oxide with warm sulphuric acid. Keep adding and stirring copper oxide to the acid until it stops dissolving and remains a solid. This means all the acid has reacted. Then filter the mixture though fnilter paper and collect the filtrate. The filtrate will just have water and soluble copper sulphate. Heat to boil of most of the water then leave to dry to allow formation of copper sulphate crystals
