Answer:
You will get 5.0 g of hydrogen.
Explanation:
As with any stoichiometry problem, we start with the balanced equation.
Sn
l
+
2HF
→
SnF
2
+
H
2
Moles of H
2
=
2.5
mol Sn
×
1 mol H
2
1
mol Sn
=
2.5 mol H
2
Mass of H
2
=
2.5
mol H
2
×
2.016 g H
2
1
mol H
2
=
5.0 g H
2
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
When the concentration is expressed in molality, it is expressed in moles of solute per kilogram of solvent. Since we are given the mass of the solvent, which is water, we can compute for the moles of solute NaNO3.
0.5 m = x mol NaNO3/0.5 kg water
x = 0.25 mol NaNO3
Since the molar mass of NaNO3 is 85 g/mol, the mass is
0.25 mol * 85 g/mol = 21.25 grams NaNO3 needed
Let's write the reaction first.
HCl + H₂O ---> H₃O⁺ + Cl⁻
These reaction has two reactants, either the proton donor or the proton acceptor. Water is amphoteric, meaning it can act as an acid or base. Since HCl is an acid, then water in this reaction acts as a base.
1. The proton donor is HCl because it donates H+ to water which yields a hydronium ion, H₃O⁺.
2. The proton acceptor is water.
Answer:
n = 0.26 mol.
Explanation:
Given,
Pressure, P = 99.7 kPa = 1 atm
where 101.325 kPa = 1 atm
P = 0.984 atm
Temperature, T = 297 K
Volume = 6.452 L
Now, using ideal gas equation
PV = n RT
0.984 x 6.452 = n x 0.08206 x 297
n = 0.26 mol.
