Explanation:
Here are the answers. Do note that I had to convert the enthalpy to joules and temperature to Kelvin to make the unit for entropy work out.
Answer:
Mass = 3 g
Explanation:
Given data:
Mass of magnesium = 2.4 g
Mass of oxygen = 2.4 g
Mass of magnesium oxide formed = ?
Solution:
Chemical equation;
2Mg + O₂ → 2MgO
Number of moles of oxygen:
Number of moles = mass / molar mass
Number of moles = 2.4 g/ 32 g/mol
Number of moles = 0.075 mol
Number of moles of magnesium:
Number of moles = mass / molar mass
Number of moles = 2.4 g/ 24 g/mol
Number of moles = 0.1 mol
now we will compare the moles of magnesium oxide with both reactant.
Mg : MgO
2 : 2
0.075 : 0.075
O₂ : MgO
1 : 2
0.1 : 2/1×0.1 = 0.2
Mass of magnesium oxide:
Mass = number of moles × molar mass
Mass = 0.075 mol × 40 g/mol
Mass = 3 g
The chemical equation is missbalaced.
The right balanced chemical equation is:
<span>2NaHCO3(s) + 129 kJ ---> Na2CO3(s) + H2O(g) + CO2(g)
Then, now you know that 2 moles of NaHCO3 requires 129 kJ heat, and you just need to convert 25.5 grams of NaHCO3 into number of moles to calculare the amount of heat needed.
A) Number of moles in 25.5 g of NaHCO3, n:
n = grams / molar mass
molar mass NaHCO3 = 23 g/mol + 1g/mol + 12g/mol + 3*16g/mol = 84 g/mol
n = 25.5 g / 84 g/mol = 0.304 mol
B) Heat required
Make the proportion with the theoretical ratio:
2mol / 129 kJ = 0.304 mol / x
=> x = 0.304 mol * 129 kJ / 2 mol = 19.608 kJ
Answer: 19.6 kJ
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Answer:
true
Explanation:
The lighter a gas is, the faster it will effuse; the heavier a gas is, the slower it will effuse. Of all the choices, helium (He) has the lowest molecular weight (atomic weight in this case), so it will have the highest rate of effusion.
