Transcript Basic Chemistry III - Univerzita Karlova v Praze

Basic Chemistry III
Vladimíra Kvasnicová
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sodium sulfite
potassium phosphate
ammonium hydrogen phosphate
lithium dihydrogen phosphate
calcium hydrogen carbonate
silver sulfide
zinc sulfate
potassium permanganate
sodium hypobromite
barium nitrate
hydrargyric chloride
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sodium tetraborate decahydrate
potassium aluminium sulfate
sodium aluminium sulfate dodecahydrate
ammonium carbonate
calcium sulfate hemihydrate
(hemi = ½)
zinc sulfate heptahydrate
potassium dichromate
potassium magnesium fluoride
ammonium magnesium phosphate
led(II) chloride fluoride
cupric biscarbonate difluoride
(bis = twice)
Important terms:
• reactants / products
• stoichiometric coefficients
• substance amount
• relative atomic / molecular mass
• molar mass
• density
• concentration (molar, percent)
molar concentration (= molarity)
M = mol/1000 mL
1M solution
 1 mol of a solute is found in 1000 mL (= 1L) of the solution
0,5M solution
 0,5 mol of a solute is found in 1000 mL (= 1L) of the sol.
percent concentration
% = g/100g
1% solution
 1 g of a solute is found in 100 g of the solution
0,5% solution
 0,5 g of a solute is found in 100 g of the solution
Chemical reactions
exercises
Calculate the mass of KOH and the volume of 96% H2SO4
needed for preparation of 25 g of K2SO4
Molar masses (MW):
KOH
56.11 g/mol
H2SO4
98.08 g/mol
K2SO4
174.26 g/mol
1. write related chemical equation
2. balance the equation
3. find the stoichiometric ratios of
reacting substance amounts
4. convert substance amounts to mass
(KOH) or volume (H2SO4)
Density of 96% H2SO4: 1.8355 g/cm3
16.1 g KOH and 7.99 mL of 96% H2SO4
Chemical reactions
exercises
5 mL of 0,5 M KMnO4 were mixed with 25 mL of Na2SO3, the
reaction processed quantitatively. Calculate concentration
of Na2SO3 (both: molarity and %).
KMnO4 + Na2SO3 + H2O → MnO2 + Na2SO4 + KOH
n=
2
3
1
Molar masses (MW):
Na2SO3
126 g/mol
KMnO4
158 g/mol
2
3
2
1. balance the chemical equation
2. find the stoichiometric ratios of
reacting substance amounts
3. convert substance amounts to
molar and % concentrations
0.15M = 1.89% Na2SO3
Chemical reactions
homework
100 g of FeS was used for the chemical reaction:
FeS + HCl → FeCl2 + H2S
1.
balance the equation
2.
calculate what volume of HCl (36%, density = 1,18 g/ml)
was needed for the reaction
3.
calculate mass of FeCl2 prepared by the reaction
Ar(Fe) = 55,8
Ar(S) = 32,1
Ar(Cl) = 35,5
Ar(H) = 1,0
Exercise
Describe dissociation of the salts:
KNO3
→
K2CO3
→
Na3PO4
→
Na2HPO4
→
NaH2PO4
→
NH4HCO3
→
What is the osmolarity of the 1M solutions?