Respuesta :
Stoichiometry time! Remember to look at the equation for your molar ratios in other problems.
31.75 g Cu | 1 mol Cu | 2 mol Ag | 107.9 g Ag 6851.65
⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻ → ⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻ = 107.9 g Ag
∅ | 63.5 g Cu | 1 mol Cu | 1 mol Ag 63.5
There's also a shorter way to do this: Notice the molar ratio from Cu to Ag, which is 1:2. When you plug in 31.75 into your molar mass for Cu, it equals 1/2 mol. That also means that you have 1 mol Ag because of the ratio, qhich you can then plug into your molar mass, getting 107.9 as well.
31.75 g Cu | 1 mol Cu | 2 mol Ag | 107.9 g Ag 6851.65
⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻ → ⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻ = 107.9 g Ag
∅ | 63.5 g Cu | 1 mol Cu | 1 mol Ag 63.5
There's also a shorter way to do this: Notice the molar ratio from Cu to Ag, which is 1:2. When you plug in 31.75 into your molar mass for Cu, it equals 1/2 mol. That also means that you have 1 mol Ag because of the ratio, qhich you can then plug into your molar mass, getting 107.9 as well.
Answer : The correct option is, (B) 107.9 grams
Explanation :
First we have to calculate the moles of [tex]Cu[/tex].
[tex]\text{Moles of }Cu=\frac{\text{Mass of }Cu}{\text{Molar mass of }Cu}=\frac{31.75g}{63.5g/mole}=0.5moles[/tex]
Now we have to calculate the moles of [tex]Ag[/tex].
The balanced chemical reaction is,
[tex]Cu+2AgNO_3\rightarrow Cu(NO_3)_2+2Ag[/tex]
From the balanced reaction we conclude that
As, 1 mole of [tex]Cu[/tex] react to give 2 mole of [tex]Ag[/tex]
So, 0.5 mole of [tex]Cu[/tex] react to give [tex]0.5\times 2=1[/tex] mole of [tex]Ag[/tex]
Now we have to calculate the mass of [tex]Ag[/tex]
[tex]\text{Mass of }Ag=\text{Moles of }Ag\times \text{Molar mass of }Ag[/tex]
[tex]\text{Mass of }Ag=(1mole)\times (107.9g/mole)=107.9g[/tex]
Therefore, the mass of Ag produced is, 107.9 grams
