Wrong questions Flashcards
State similarity between the atomic structures of isotopes of the same element
same no of protons AND electrons
A sample of magnesium, 24.305 is found ti consist of 3 isotopes
TABLE
24Mg, relative isotopic mass= 23.985, %78.99
25Mg, relative isotopic mass= 24.986 %10
Determine the relative isotopic mass of the third isotope to 5sf
24.305 = (23.985 x 78.99) + (24.986 x 10.00) + (M x 11.01) /100
2430.5 = 2144.43515 + (M x 11.01)
286.06485 = (M x 11.01)
M = 25.9822752
Formule of sodium sulphate
Na2SO4
Formula of potassium sulphite
K2SO3
Formula of silver chloride
AgCl
A student adds a sample of solid potassium carbonate to an excess of dilute sulfuric acid. Describe what the student would SEE and write the equation for the reaction which takes place (3)
Gas produced/effervescence
K2CO3 dissolves/disappears and a colourless solution is formed
H2SO4+K2CO3->K2so4 +co2+ h2o
calcium phosphate is another salt used in fertilisers, calcium phosphate can be prepared by reacting together an acid and a base, suggest the formula of the acid used to prepare calcium phosphate(1)
H3PO4
calculate the value of n in HOOC(CH2)nCOOH, the mean titre is 18.25 and the concentration is 0.240
2.891g of glutaric acid is dissolved in 250cm^3, 25cm^3 of this is transferred
0.24x 18.25/1000= 0.00438
acid in 25cm= 0.00438/2= 0.00219x10 for 250
mr of acid=2.891/0.0219=132
132-90(COOHX2)= 42/14
n=3
A 25cm3 pipiette was used and before use, was washed out with water instead of the solution, whats the effect
less glutamic acid as water will dilute/reduce the concentration
explain which block the periodic table sodium and magnesium belong to
they belong to the s block as their outer electrons highest energy is in the s orbital
explain why a cf4 molecule has polar bonds but not an overall dipole
cf4 is tetrahedral and symmetrical and flueone is more electronegative so has an overall dipole
explain why h2o has a higher boiling point than h2se(3)
h2o can hydrogen bond whereas h2se has london forces
the hydrogen bonds are stronger so more energy is needed to overcome this
ca(oh)2 is used in agriculture to neutralise —— soils
ACIDIC
explain how the successive ionisation energies provide evidence that magnsium is in group 2 of the periodic table
large difference between 2 and 3/ big jump
describe 2 observations which would be different if the student used calcium in the place of strontium
less effervescence
ph less alkaline
Q6
- reactivity decreases down the group
- as the atomic radius incrwases increasing shielding
- resulting in less nuclear attraction
4.br2+2i- ->2br- + 12
5.. orange contains bromine= no reaction, iodine is violet
Q8
c=na2so4
sulfate=precipitate
