C5 Flashcards
Recall the formula of hydrochloric acid, ethanoic acid, carbon dioxide, hydrogen, water, sodium chloride, potassium chloride, ammonia and calcium carbonate
HCl, CH3COOH, CO2, H2, H2O, NaCl, KCl, NH3, CaCO3
recall the formula for: sulfuric acid, nitric acid, sodium hydroxide, potassium hydroxide, magnesium carbonate, sodium sulfate, potassium sulfate, magnesium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, barium sulfate, lead (II) nitrate, lead iodide, potassium iodide and potassium nitrate
H2SO4, HNO3, NaOH, KOH, MgCO3, Na2SO4, KSO4, MgSO4, BaSO4, Pb(NO3)2, PbI2, KI, KNO3
What is the relative atomic mass of an atom
The average mass of an atom of the element in comparison to the mass of 1/12th of a carbon 12 atom
Formula for moles
Number of moles = Mass/ molar mass
Cm3 to Dm3
Divide by 1000
Amount of moles =
Concentration X volume
1G of salt =
0.393g of sodium
Why should an acid based titration use a single indicator rather than a mixed imdicator
Because it gives a sudden colour change at the end point. Mixed indicator won’t give you the precise end point of a titration.
Mixed indicator = universal indicator
Single indicator= phenolphthalein (changes from pink to colourless)
How to measure the volume of gas
Use a gas syringe. Connect the syringe to the reaction container with the tube and as the reaction is carried out and gas is produced, gas will fill the syringe and push the plunger out. The graduations on the side show the volume of gas contained in the gas syringe.
Upturned measuring cylinder in a trough of water with connected tube. Air pressure will keep the water inside the cylinder. Delivery tube from the cylinder to the reaction container. As reaction occurs, gas fills the upturned cylinder snd pushes water out. Graduations on the side show the amount of gas collected. Same as upturned displacement (with an upturned burette). This is only accurate if the gas is not very soluble in water so not co2.
What happens at equilibrium
The rate of the forward reaction= the rate of the backwards reaction
Concentrations of products do not change.
The position of equilibrium is on the left is the concentration of reactions is greater than the concentration of products.
On the right of the concentration of products is greater than the concentration of reactants
How can a reversible reaction reach equilibrium
In a Closed system eg stopped flask or beaker. If the system is open the reacting substances may escape and equilibrium will not be reached.
Initially rate of forward reaction decreases, rate of backward reaction increases. Eventually they are the same
What does : Removing a product Adding a product Removing a reactant Adding a reactant Increasing pressure Increasing temperature
Removing product: moves to right
Adding product: moves to left
Removing reactant: moves to left
Adding reactant: moves to right
Increasing pressure: moved to the side with the least moles
Decreasing pressure: moved to side with more moles
Increasing temperature: favours the endothermic side of the reaction
Decreasing temperature: favours the exothermic side
Explain the contact process
Need : sulfur, air, oxygen
1: sulfur burned in air to make sulfur dioxide
S+ O2 –> SO2
2: sulfur dioxide burned with oxygen to make sulfur trioxide
2SO2 + O2 –> 2SO3
3: SO4 + H2O –> H2SO4
What conditions are needed for the contact process
V2O2 catalyst
Greater yield can be obtained by reducing the temperature because the forward reaction is exothermic
High enough temperature needed for a fast rate of reaction (450)
Atmospheric pressure used because it is to the right. High pressure would increase the yield but increasing the pressure would increase the cost and it wouldn’t be worth it because there is only a small increase in yield.
Acid ionises water to produce which ions
h+ ions
What is the difference between a strong acid and a weak acid
The ph of a weak acid is higher than a ph of a strong acid.
Acid strength is is a measure of the degree of ionisation of the acid. How much it ionises. Strong acids completely ionise in water. Weak acids partially ionise.
Weak acids form reversible reactions
What is the concentration of an acid
It is a measure of the number of moles of acid in one dm3
Why does ethanoic acid react slower than hydrochloric acid with the same concentration
Because ethanoic acid has a lower concentration of hydrogen io s. In ethanoic acid the hydrogen ions have a lower collision frequency with reactant particles.
Explain why ethanoic acid is less conductive than hydrochloric acid of the same concentration
Because in weak acids there are less hydrogen ions so it is more difficult for a current to pass through.
Why are precipitation reactions fast
The collision frequency between ions is large so there is a high chance that different ions will collide and cause a reaction.
Precipitates for, as soon as two suitable solutions are mixed together
Barium chloride + sodium sulfate —>
Barium sulfate + sodium sulfate
