Summary
Summary - Unit 5 - Formulae, Equations and Amounts of Substance
- Institution
- PEARSON (PEARSON)
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FORMULAE EQUATIONS AND AMOUNT OF SUBSTANCE .3
EMPIRICAL FORMULA IDEAL GAS EQUATION : MAKING STAN
A compound contains 23 3% .
Magnesium ,
30 7 % Sulfur
. WEIGH out the amount
and 46 0 % oxygen
.
.
What is the empiracle formula of the compound ? TRANSFER the solid to a
bea
Mg S O WRITE OUT INVOLVED (Pa) (8 31 s umo) DISSOLVE fully using distille
-
.
ELEMENTS
w&
46 TRANSFER
39 30
7g Og WRITE PERCENTAGES volumetric f
most
23 .
.
. into a
= 32 1 = 16 As MASSES
- 24 3
.
.
0 96 i0 96
i 2 88 .
M
FILL to the
graduation
Mr
. .
96
What volume of He is produced when h reacts
+ 0 96 =0 . 96 :0 .
n =
with 100upa
.
water at of
pressure and 2984
.
Gas constant is 8 31 Ju "mol" -
.
I W I ↳ 3 SIMPLIFY MIX the contents by
write equation 2k1s + 2HeOw ->IKOMinas + H2 19)
MgSOz WRITE OUT COMPOUND substitute into the
equation 1 = g 1
2 : /
0 3 2 = 0 15 Mol
pV
avog
= .
nRT
.
particles
=
No. =
V = 0 15x8 31 298
ldns)
. . x
volume
-
EMPIRACLE FORMULA-simplest 100 000 What
whole ratio of of each is the ions in 9
53g
no. element in a compound
atoms no
of M
·
.
10 3 m3
-
3 8
gas volume S
x
molar
=
MOLECULAR FORMULA -
the actual no · of arams of each element present in a compound ·
n = .
= 0 .
/mo
of gas X3
MOLARVOLUME OF GAS
-
volume occupied by one more understandard conditions utp X10 . ions
t XArconstant 0 3 x 16 02 x 1023)
24 am
.
.
= 1 . 806 x 1023
standard room temperature
: 293
k
101 3 uPa
ERRORS AND UNCERTAINTY
pressure .
UNCERTAINTY-half the smallest increment on equipment leg =0 .
05cm3) PERCENTAGE ERROR =
S
↳ reduce
value : 21 cm error by :
margin of error : 20 .
95[X]21 . 05
IScm3 of 1 15
. moldm-3 NaOH neutralises 34 2 c .
The volume of HNOz has of 0 2 cm
on
Uncertainty .
Calc .
uncertainty of HNOz 02
A cylinder is used measured to the nearest 10cm" alongside a burette which 34 2 .
x100 = 0
calc .
%
Uncertainty of NaOH 0 04.
measures to the nearest 0 1 cm3
. Ts x 100 = 0
Calc %
uncertainty total
0 58 + 0 27 = 0
work out
.
uncertainty
.
the total .
SYSTEMATIC ERRORS -
ca
Cylinder 10/2 = t5cm3 total uncertainty
=
0 05 + S
.
burette 0 1/2 = = 0 OScm3
= I5 05 cm3
.
RANDOM
.
ERRORS es
.
-
never 100 %1 amounts
ACTUAL YIELD cm3
e .
g gor
.
PERCENTAGE YIELD :
THEORETICAL YIELD X 100 less waste
~
↳ productivity
(multiply x2 if Imoles'
More sustainab
Mr OF DESIRED PRODUCT
/REMEMBER
-
Mr !)
>
-
-
ECONOMY X
ATOM = SUM OF ALL REACTANTS Mr 100 less by-produc
↳ efficiency
↳ should be 100 % for
always
addition reactions
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