Respuesta :
Answer:
Approximately [tex]0.6003\; \rm mol[/tex] formula units.
Explanation:
Formula Mass of KClO₃
Look up the relative atomic mass data for [tex]\rm K[/tex], [tex]\rm Cl[/tex], and [tex]\rm O[/tex] on a modern periodic table:
- [tex]\rm K[/tex]: [tex]39.908[/tex].
- [tex]\rm Cl[/tex]: [tex]35.45[/tex].
- [tex]\rm O[/tex]: [tex]15.999[/tex].
The relative atomic mass of an element is numerically equal to the mass (in grams) of one mole of its atoms. For example, the relative atomic mass of [tex]\rm K[/tex] is [tex]39.908[/tex]. Therefore, the mass of one mole of [tex]\rm K\![/tex] atoms should be [tex]39.908\; \rm g[/tex].
Each [tex]\rm KClO_3[/tex] "formula" unit includes one [tex]\rm K[/tex] atom, one [tex]\rm Cl[/tex] atom, and three [tex]\rm O[/tex] atoms. Therefore, one mole of [tex]\rm KClO_3\![/tex] formula units would include:
- one mole of [tex]\rm K[/tex] atoms,
- one mole of [tex]\rm Cl[/tex] atoms, and
- three moles of [tex]\rm O[/tex] atoms.
From the relative atomic mass of these three elements:
- The mass of one mole of [tex]\rm K[/tex] atoms would be [tex]39.908\; \rm g[/tex].
- The mass of one mole of [tex]\rm Cl[/tex] atoms would be [tex]35.45\; \rm g[/tex].
- The mass of three moles of [tex]\rm O[/tex] atoms would be [tex]3 \times 15.999\; \rm g = 47.997\; \rm g[/tex].
Combining these three parts should give the mass of one mole of [tex]\rm KClO_3[/tex] formula units:
[tex]\begin{aligned}& M(\mathrm{KClO_3}) \\ &= 39.908 + 35.45 + 3 \times 15.999 \\ &= 122.545\; \rm g \cdot mol^{-1}\end{aligned}[/tex].
Number of moles of KClO₃ formula units in the sample
The formula mass of [tex]\rm KClO_3[/tex] is [tex]M(\mathrm{KClO_3}) = 122.545\; \rm g \cdot mol^{-1}[/tex], meaning that the mass of one mole of [tex]\rm KClO_3\![/tex] formula units would be [tex]122.545\; \rm g\![/tex].
The mass of this [tex]\rm KClO_3\!\![/tex] sample is [tex]m(\mathrm{KClO_3}) = 73.56\; \rm g[/tex]. The number of moles of formula [tex]\rm KClO_3\![/tex] units in this sample would be:
[tex]\begin{aligned}n(\mathrm{KClO_3}) &= \frac{m(\mathrm{KClO_3})}{M(\mathrm{KClO_3})} \\ &= \frac{73.56\; \rm g}{122.545\; \rm g \cdot mol^{-1}} \approx 0.6003\; \rm mol\end{aligned}[/tex].
73.56 g of potassium chlorate (v), KClO₃ contains 0.6 mole of potassium, K.
To know the exact number of mole of potassium (K) in 73.56 g of potassium chlorate (v), KClO₃ do the following:
Step 1:
Determination of the number of mole in 73.56 g of potassium chlorate (v), KClO₃
Mass of KClO₃ = 73.56 g
Molar mass of KClO₃ = 39 + 35.5 + (16×3)
= 39 + 35.5 + 48
= 122.5 g/mol
Mole of KClO₃ =?
[tex]Mole =\frac{mass}{molar mass}\\\\Mol KClO_{3} = \frac{73.56}{122.5}[/tex]
Mole of KClO₃ = 0.6 mole
Step 2:
Determination of the number of mole of potassium, K in 0.6 mole (i.e 73.56 g) of KClO₃
Considering the molecular formula of potassium chlorate (v), KClO₃, we can see that:
1 mole of KClO₃ contains 1 mole of K.
Therefore, 0.6 mole of KClO₃ will also contain 0.6 mole of K.
Therefore, we can conclude that 73.56 g of KClO₃ contains 0.6 mole of potassium, K.
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