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
The gas is NH₃.
H₂ doesn't dissolve readily in water, SO₂ gives an acidic solution in water.
The solid residue is Fe(OH)₂.
FeSO₄ and Na₂SO₄ are soluble in water.
The answer is C.
Answer:
-------> 
+ 
Explanation:
In equation 1, equating the mass number (A) on both sides.
A = 235 + 1 = A + 94 + 3*1
236 = A + 94 + 3
A = 236 - 94 = 3
A = 139
Equate the atomic numbers on both sides
92 + 0 = Z + 36 + 3*0
92 = Z + 36
Z = 92 - 36
Z = 56
In reaction 2, equating the mass number on both sides
235 + 1 = A + 143 + 3 *1
236 = A + 143 + 3
236 = Z + 146
Z = 90
Equatoing the atomic number of both sides
92 + 0 = Z + 54 + 3*0
92 = Z + 54
Z = 92 - 54
Z = 38.
Answer:
236.9g
Explanation:
Given parameters:
Volume of gas = 81.3L
Pressure of gas = 204kPa
temperature of gas = 95°C
Unknown:
Mass of carbondioxide gas = ?
Solution:
To solve this problem, the ideal gas law will be well suited. The ideal gas law is a fusion of Boyle's law, Charles's law and Avogadro's law.
Mathematically, it is expressed as;
PV = nRT
the unknown here is n which is the number of moles;
P is the pressure, V is the volume, R is the gas constant and T is the temperature.
convert pressure into atm
101.325KPa = 1atm
204 kPa = 
= 2atm
Convert temperature to Kelvin; 95 + 273 = 368K
2 x 81.3 = n x 0.082 x 368
n = 
= 5.38moles
Since the unknown is mass;
Mass = number of moles x molar mass
Molar mass of carbon dioxide = 12 + 2(16) = 44g/mol
Mass = 5.38 x 44 = 236.9g
Answer:
A, B, and C
Explanation:
Atoms do in fact have mass! They are also the basic unit of a chemical element. Matter is in fact made of atoms, but atoms do not take up space.
Atoms are filled with empty space, excluding it out from the rest of the answers.
So yes, A, B, and C should be the correct answers
