Answer:
0.18 mol
Explanation:
Given data
Step 1: Convert the mass of the solvent to kilograms
We will use the relationship 1 kg = 1,000 g.
Step 2: Calculate the moles of the solute
The molality is equal to the moles of solute divided by the kilograms of solvent. Then,
Answer:
Option 3. The catalyst does not affect the enthalpy change () of a reaction.
Explanation:
As its name suggests, the enthalpy change of a reaction () is the difference between the enthalpy of the products and the reactants.
On the other hand, a catalyst speeds up a reaction because it provides an alternative reaction pathway from the reactants to the products.
In effect, a catalyst reduces the activation energy of the reaction in both directions. The reactants and products of the reaction won't change. As a result, the difference in their enthalpies won't change, either. That's the same as saying that the enthalpy change of the reaction would stay the same.
Refer to an energy profile diagram. Enthalpy change of the reaction measures the difference between the two horizontal sections. Indeed, the catalyst lowered the height of the peak. However, that did not change the height of each horizontal section or the difference between them. Hence, the enthalpy change of the reaction stayed the same.
Answer:
Percent yield = 92.5%
Explanation:
The question asks for the percent yield which can be defined as:
Where the actual yield is <em>how much product was obtained</em>, in this case 6.11 g of Ca(OH)₂, and the theoretical yield is <em>how much product could be obtained with the given reactants theoretically</em>, that is if the reaction would work perfectly. So we need to calculate first the theoretical yield.
1. First lets write the chemical equation reaction correctly and check that it is balanced:
CaO + H₂O → Ca(OH)₂
2. Calculate the amount of product Ca(OH)₂ that can be obtained with the given reactants (theoretical yield), which are 5.00g of CaO and excess of water. So the amount of CaO will determined how much Ca(OH)₂ we can obtained.
For this we'll use the molar ratio between CaO and Ca(OH)₂ which we see it is 1:1. For every mol of CaO we'll obtain a mol of Ca(OH)₂. So lets convert the 5.00 g of CaO to moles:
Molar Mass of CaO: 40.078 + 15.999 = 56.077 g/mol
moles of CaO = 5.00 g / 56.077 g/mol = 0.08916 moles
As we said before from the molar ratio moles of Ca(OH)₂ = moles of CaO
So the moles of Ca(OH)₂ that can be obtained are 56.077 g/mol
We need to convert this value to grams:
Molar Mass of Ca(OH)₂ = 40.078 + (15.999 + 1.008)*2 = 74.092 g/mol
Theoretical yield of Ca(OH)₂ = 0.08916 moles x 74.092 g/mol = 6.606 g
3. Calculate the percent yield:
Percent yield = (6.11 g / 6.606g) x 100 = 92.5 %