a) The reaction is exothermic since the overall enthalpy change is negative. this means that the system has lost energy to the environment, namely, the apparatus and due to drought.
b) We first calculate the number of moles in 3.55 grams of magnesium.
number of moles= mass/ atomic mass
=3.55/24
=0.1479 moles(to 4sf)
now, if 2 moles of magnesium give -1204kJ
How much energy is given by 0.1479 moles
= (0.1479×-1204kJ)
=-89.0358kJ (don't forget the negative sign)
c) two molesof MgO produces -1204kJ of energy
then -234kJ will be produced by
=(-234kJ×2moles)/1204kJ
=0.3887moles
one mole of MgO weighs 24+16=40
therefore the mass produced is 0.3887moles×40=15.548grams
(d) we first find the number of moles of MgO in 40.3 grams
number of moles=mass/RFM
=40.3g/40= 1.0075moles
if 2 moles of MgO give 1204 kJ then decomposing 1.0075 moles requires
(1.0075 moles×1204kJ)/2=606.515kJ
Answer: 2 mol
Explanation:
- According to the ideal gas law, One mole of an ideal gas at STP (standard temperature and normal pressure) occupies 22.4 liters.
- Using cross multiplication,
1 mol of (O2) → 22.4 L
? → 43.9 L
Therefore, the number of moles of oxygen in 43.9 L = (43.9 × 1)/ 22.4 = 1.96 mol≈ 2 mol..
The puppies have different colored noses because of reccesive and dominant genotypes.
Genotypes are represented by letters, capital being dominant and lowercase being recessive.
For example, lets say t = pink nose and T = black nose.
If the parents have black noses, then they will pass on T genotypes.
But, they also have hidden pink nose genotypes.
These hidden genotypes are passed on to the puppies, one of the puppies gets more black nose genotypes.
If a puppy gets tt, they will have a pink nose.
If they get TT, they will have a black nose
If they get Tt, they will also have a black nose.
Because the black nose is dominant, its more likley for the puppies to end up with a black nose.
- 3.5
- 9
- 24.7
- 8.01
- 0.006
- 13(1.25×1012=12.65)
Explanation:
Above we have simply looked the condition that where we put decimal point that gives your needed answer after round off.
For example:
we have to make 2 s.f from 345 so we kept decimal after 3 and we rounded off to make 3.5 from 3.45
Hope you got it
Crystallize below earths surface
