Answer:
34.33 %.
34.33 %.
34.33 %.
Explanation:
- To calculate the mass percent or weight percent of a solution, you must divide the mass of the solute by the mass of the solution (both the solute and the solvent together) and then multiply by 100 to change it into percent.
<em>W% = [(W of solute NaF)/(W of solution)] x 100.</em>
<em></em>
W of solute NaF = 65.4 g.
W of solution = W of solute NaF + W of water = 65.4 g + 125.1 g = 190.5 g.
∴ W% = [(W of solute NaF)/(W of solution)] x 100 = [(65.4 g)/(190.5 g)] x 100 = 34.33 %.
Answer:
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^2
Explanation:
<span>Hess' Law states that the enthalpy change in a reaction can be calculated from the enthalpy changes of reactions that, when combined, result in the desired reaction.
For example, to check the enthalpy change that occurs when benzene undergoes incomplete combustion to water and carbon monoxide is not an easy task, because the products invariably contain CO2. However, by combining the reactions of the complete combustion of benzene and the combustion of CO, you can get the reaction you want.
Reaction wanted: 2C6H6 + 9O2 → 12CO + 6H2O
Reactions provided: 2C6H6 + 15O2 → 12CO2 + 6H2O and 2CO + O2 → 2CO2, and their associated ΔH.
Rearrange the reactions so that, when they add up, they result in the wanted reaction.
2C6H6 + 15O2 → 12CO2 + 6H2O (leave as is; no changes to ΔH)
12CO2 → 12CO + 6O2 (reverse and multiply by 6; this changes the sign of ΔH and multiplies it by 6)
Added up, it will result in 2C6H6 + 9O2 → 12CO + 6H2O. Add up the ΔH values for the rearranged reactions to find ΔH for this particular reaction.</span>
So if we use the equation:
→ 
We can then determine the amount of 
needed to produce 208 kg of methanol.
So let's find out how many moles of methanol 208 kg is:
Methanol molar weight = 32.041g/mol
So then we can solve for moles of methanol:
So now that we have the amount of moles produced, we can use the molar ratio (from the balanced equation) of hydrogen and methanol. This ratio is 2:1 hydrogen:methanol.
Therefore, we can set up a proportion to solve for the moles of hydrogen needed:
So now that we have the number of moles of 
that are produced, we can then use the molar weight of hydrogen to solve for the mass that is needed:
Therefore, the amount of diatomic hydrogen () that is needed to produce 208kg of methanol is 
g.
Answer:
6.48L
Explanation:
Given parameters:
V₁ = 2.5L
P₁ = 105 kPa
P₂ = 40.5 kPa
Condition: constant temperature
Unknown:
V₂ = ?
Solution:
To solve this problem, we are considering pressure and volume relationship. This should be solved by applying the knowledge of Boyle's law.
The law states that "The volume of fixed mass of a gas varies inversely as the pressure changes if the temperature is constant".
Mathematically;
P₁V₁ = P₂V₂
where P and V are pressure and volume, 1 and 2 represents initial and final states.
Substitute to find the V₂;
105 x 2.5 = 40.5 x V₂
Solving for V₂ gives 6.48L
