The values of x represents that number of moles of water molecules that is present per mole of the salt magnesium sulfate. To determine the value for this, we need to know how much is the water that is lost after heating the sample assuming that all of the water molecules are evaporated leaving only the unhydrated form of the salt. We calculate as follows:
Mass of hydrated salt = 3.484 g
Mass after heating = 1.701 g
Mass lost = 3.484 g - 1.701 g = 1.783 g
The mass lost is equal to the mass of water lost.
Moles water lost = 1.783 g ( 1 mol / 18.02 g ) = 0.0989 mol H2O
Moles of unhydrated salt = 1.701 g ( 1 mol / 120.37 g ) = 0.0141 mol MgSO4
moles water / moles MgSO4 = 0.0989 mol H2O / 0.0141 mol MgSO4 = 7
Therefore, the value of x is 7.
Answer:
429.4 kJ are absorbed in the endothermic reaction.
Explanation:
The balanced chemical equation tells us that 1168 kJ of heat are absorbed in the reaction when 4 mol of NH₃ (g) react with 5 mol O₂ (g).
So what we need is to calculates how many moles represent 25 g NH₃(g) and calculate the heat absorbed. (NH₃ is the limiting reagent)
Molar Mass NH₃ = 17.03 g/mol
mol NH₃ = 25.00 g/ 17.03 g/mol = 1.47 mol
1168 kJ /4 mol NH₃ x 1.47 mol NH₃ = 429.4 kJ
Answer:
The SI base units of length, mass, and time are the meter (m), kilogram (kg), and second (s), respectively. SI units are a metric system of units, meaning values can be calculated by factors of 10. Metric prefixes may be used with metric units to scale the base units to sizes appropriate for almost any application
Answer:
A. 8.8 g.
B. 5.3 g.
C. 449 g.
Explanation:
A. Determination of the mass of CO2.
Mole of CO2 = 0.2 mole
Molar mass of CO2 = 12 + (2×16)
= 12 + 32
= 44 g/mol
Mass of CO2 =?
Mole = mass /Molar mass
0.2 = mass of CO2 /44
Cross multiply
Mass of CO2 = 0.2 × 44
Mass of CO2 = 8.8 g
B. Determination of the mass of Na2CO3.
Mole of Na2CO3 = 0.05 mole
Molar mass of Na2CO3 = (2×23) + 12 + (3×16)
= 46 + 12 + 48
= 106 g/mol
Mass of Na2CO3 =?
Mole = mass /Molar mass
0.05 = mass of Na2CO3 /106
Cross multiply
Mass of Na2CO3 = 0.05 × 106
Mass of Na2CO3 = 5.3 g
C. Determination of the mass of Fe(OH)2.
Mole of Fe(OH)2 = 5 moles
Molar mass of Fe(OH)2 = 55.8 + 2(16 + 1)
= 55.8 + 2(17)
= 55.8 + 34
= 89.8 g/mol
Mass of Fe(OH)2 =?
Mole = mass /Molar mass
5 = mass of Fe(OH)2/89.8
Cross multiply
Mass of Fe(OH)2 = 5 × 89.9
Mass of Fe(OH)2 = 449 g.