C4 - Chemical Calculations
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Equation for moles?
Moles = mass (g) / Mr
How are the masses of atoms found?
By measuring them relative to carbon 12
Balanced symbol equation tells you what?
The number of moles of substances in equations.
What is a limiting reactant?
The one NOT in excess, which gets used up first.
E. Moles of a gas?
Moles = volume / 24dm3
What is Avogadro constant?
The number of particles contained in a mole. 6.02*10 to the 23
Examples of strong acids? (3)
Hydrochloride acid, nitric acid and sulfuric acid.
Examples of strong alkalis? (2)
Aqueous sodium hydroxide and aqueous potassium hydroxide
Suitable indicators for titrations? (2)
Methyl orange and phenolphthalein
When doing a titration, where does the 1) acid 2) alkali Go?
Acid in the burette Alkali in the conical flask (with indicator)
What information must be known to fund the concentration of an acid/alkali from a titration?
The relative bylines of acid and alkali used The conc. of other acid/alkali.
E. Percentage yield?
Yield from reaction/maximum theoretical yield * 100%
Why is atom economy important?
To minimise costs, sustainable development so less waste is produced.
E. Atom economy?
Atom economy = relative formula mass of desired product / sun of the relative formula mass of all the products or reactants. *100%
How can ethanol be produced?
Hydration and fermentation?
How does hydration of ethanol work?
Ethene reacts with steam to form ethanol.
How does fermentation of ethane work?
Glucose is fermented.
Which way of production of ethanol has a higher atom economy?
Hydration.
Factors to consider when choosing a reaction pathway? (6)
• atom economy • cost of reactants • percentage yield • rate of reaction • equilibrium position • usefulness of the by-products.
In electrolysis if aqueous solutions , what is produced at the anode?
Oxygen unless it contains halide ions. If halide ions are produced then the halogen is given off.
In electrolysis if aqueous solutions , what is produced at the cathode?
Hydrogen if the metal is more reactive then hydrogen. The metal is produced if the metal is less reactive then hydrogen.
Which metals can be extracted from their idea using electrolysis?
Metals more reactive then carbon.
What is a 1 on the ph scale?
Very Acidic
What is 7 on the pH scale?
Neutral