Guess and check, test, trial and error, completion.
Answer:
Na₂CO₃.2H₂O
Explanation:
For the hydrated compound, let us denote is by Na₂CO₃.xH₂O
The unknown is the value of x which is the amount of water of crystallisation.
Given values:
Starting mass of hydrate i.e Na₂CO₃.xH₂O = 4.31g
Mass after heating (Na₂CO₃) = 3.22g
Mass of the water of crystallisation = (4.31-3.22)g = 1.09g
To determine the integer x, we find the number of moles of the anhydrous Na₂CO₃ and that of the water of crystallisation:
Number of moles = 
Molar mass of Na₂CO₃ =[(23x2) + 12 + (16x3)] = 106gmol⁻¹
Molar mass of H₂O = [(1x2) + (16)] = 18gmol⁻¹
Number of moles of Na₂CO₃ = 
= 0.03mole
Number of moles of H₂O = 
= 0.06mole
From the obtained number of moles:
Na₂CO₃ H₂O
0.03 0.06
Simplest
Ratio 0.03/0.03 0.03/0.06
1 2
Therefore, x = 2
Actually the strength
of London dispersion forces highly depend on the total number of electrons and
the area in which they are spread. We can see clearly that iodine will have the
strongest LDF's, and hence, have the highest boiling point (and melting point).
This is also the reason why iodine is a solid at room temperature, bromine is liquid
and chlorine and fluorine are gases.
Answer:
<span>Fluorine (F2)</span>
Diluted by a factor of two means that we double the volume of the solution by adding an equal volume of the water.
if we diluted it by a factor of one so the new concentration = 0.1/2=0.05 M and diluted by a factor of two so, the new concentration will be 0.05/2 = 0.025 M
Answer:
the average molar mass of this air sample can be calculated as
addition of the product of the average molar weights of the component gases and their percentage compositions
1. Average Molar mass of Air = 0.7803 x 28 + 0.2099 x 32 + 0.00033 x 44 = 28.58g/mol
2. The partial pressures of N2, O2, and CO2 in atm.
From Ideal gas law, at stp, Volume of air V=22.4L/mol
PV =nRT
Since, at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of the gas
Total Pressure P=1atm
Partial Pressure p = mol fraction x P
Volume of N2 = 0.7803 x 22.4L = 17.47L, Partial Pressure = 0.7803atm
Volume of O2 = 0.2099 x 22.4L = 4.68L Partial Pressure = 0.209atm
Volume of CO2 = 0.00033 x 22.4L = 0.00739L, Partial Pressure = 0.033atm
