Answer:
Explanation:
250 cm^3 of 0.2 moldm-3 H2SO4 can be prepared from 150cm^3 of 1.0 moldm^-3 by dilution.
150cm^3 of the 1.0 moldm^-3 stock solution is measured out using a measuring cylinder and transferred into a 250 cm^3 standard volumetric flask and made up to mark. The resulting solution is now 250cm^3 of 0.2 moldm-3 H2SO4.
The answer is 60.3% magnesium, 39.7% oxygen.
Solution:
The chemical equation for the reaction is 2 Mg + O2 → 2 MgO.
Since magnesium reacts completely with oxygen, it is the limiting reactant in the reaction. Hence, we can use the number of moles of magnesium to get the mass of MgO produced:
moles of magnesium = 14.7g / 24.305g mol-1
= 0.6048 mol
mass of MgO = 0.6048mol Mg(2 mol MgO/2mol Mg)(40.3044g MgO/1 mol MgO)
= 24.376g MgO
We can now solve for the percentage of magnesium:
% Mg = (14.7g Mg / 24.376g MgO)*100% = 60.3%
We also use the number of moles of magnesium to get the mass of oxygen consumed in the reaction:
mass of O2 = 0.6048 mol Mg (1mol O2 / 2mol Mg) (31.998g / 1mol O2)
= 9.676g
The percentage of oxygen is therefore
% O2 = (9.676g O2 / 24.376g MgO)*100%
= 39.7%
Notice that we can just subtract the magnesium's percentage from 100% to get
% O2 = 100% - 60.3% = 39.7%
Answer:
~1.417M
Explanation:
Molarity=(number of moles of solute)/(litres of solution)
In this case, we need to find moles of potassium bromide.
Mass=25.3g
Molar mass= 119g/mol
moles=(mass/molar mass)
=(25.3)/(119)
=0.2126moles of potassium bromide
Molarity=(0.2126)/(150/1000)
~1.417M
Hope this helps:)
Depends on the situation. If the nucleophile is already in excess, then no the reaction will not occur faster
There are MANY subatomic particles in an atom.
But the three most important ones are
The electron which has a negative charge.
The proton having a positive charge.
And the neutron which is neutral or which has no charge at all.
The protons and neutrons club together and form the inner, heavy part of the atom which is positively charges because of the protons known as the nucleus.
And electrons remain farther away in all reality and revolve around the inner positive nucleus.
Trying its best to make the whole atom neutral!
