Last Minute Cards

[1] Average mass of an atom of an element [2] Compared to 1/12th the mass of an atom of carbon-12

[1] Weigh out sample in bottle / boat / container [2] Transfer to (conical) flask / beaker (or suitable container) and wash all sample in [3] Dissolve sample in water [4] Add into volumetric flask with washings [5] make up to mark / 250 cm3 in volumetric flask [6] shake / invert

Heat change in a reaction at a constant pressure

100kPa 298K

Minimum amount of energy required for reaction

Pour approximately 100cm3​ ​ of the standard solution of known concentration into a beaker Fill the burette with the standard solution of known concentration Pour approximately 100cm3​ ​ of the solution with unknown concentration into a second beaker Using a pipette filler and pipette to transfer exactly 25cm3​ ​ of solution into a 250cm3​ ​ conical flask Add indicator Record the initial burette reading Titrate and record final Repeat until concordant results

Using a more accurate balance or a larger mass will reduce the uncertainty in weighing a solid Weighing by difference Replacing measuring cylinders with pipettes or burettes which have lower apparatus uncertainty will lower the overall error. To reduce the uncertainty in a burette reading the titre volume needs to be made larger

Weigh out drying agent and record to a precise amount. Place 25cm3 of deionised water into a polysterene cup and record initial temperature. Start timer and record temp for first three minutes. At the fourth minute, add first reagent and began recording in minute intervals at 5 minutes again. Stir continuously as this occurs and a lid may prevent heat loss.

Electronic temperature sensor. Data logging software for graph. Flame calorimeter.

Add 10cm3 of HCl to a test tube Add 10cm3 of sodium thiosulfate to a test tube with a black X cross under it. Carefully insert thermometer and record initial temperature. Add 1cm3 of acid to test tube and start stopcock. Record time taken for X to disappear Record final temperature and pour into sodium carbonate solution to prevent SO2 Do at different temperatyre by warming with a water bath

Add barium chloride Add sodium hydroxide Continue adding NaOH until excess while shaking gently

BaCl2 - Colourless CaBr2 - Slight white precipitate MgCl2 - Slight white ppe to white ppe in excess NaOh SrCl2 - Slight white precipitate

Add barium chloride Add sulfuric acid Continue adding sulfuric acid until excess while shaking gently

BaCl2 - White precipitate CaBr2 - Slight white precipitate MgCl2 - Slight white ppe to colourless in excess sulfuric acid SrCl2 -White precipitate

Tendancy of an atom to attract a pair of electrons

6I- + 6H+ H2SO4 –> S + 3I2 + 4H2O

Bonding: Each C has 3 covalent bonds, spare electrons overlap, delocalisation Shape: Planar, hexagonal, C-C bonds equal in length Stability: Expected -360, less exothermic by 152, benzene is more stable

[1] Value within range –239 to –121 [2] Double bonds separated by one single bond / alternating [3] Allows some delocalisation/overlap of p orbitals

HCOCl + AlCl3 → [HCO]+ + [AlCl4]−

Add 50cm3 of 0.8 HCl to a conical flask. Set up gas syringe equipment. Add a 6cm strip of Mg ribbon to a conical flask, place the bung firmly on top of the flask. Record volume of H gas every 15 seconds for 2.5 minutes. Alter HCl concentration and repeat steps.

Measure known conc and volume of 2 out of 3 reactants Add a known conc of and volume of X to the container Measure known conc and volvume of C in a seperate beaker Add C and and start the timer. Record time for blue - black colour to appear. Repeat with different conc of A but keep all other variable the same. Calculate rater which is 1/time. Plot a graph which is rate compared to concentration. Interpret rate using graph.