8g of #"E"_2"O"_3# contain 5.6g of #"E"#. How many moles of #"E"# does a 16.8-g smaple of element #"E"# contain?

Question

8g of #"E"_2"O"_3# contain 5.6g of #"E"#. How many moles of #"E"# does a 16.8-g smaple of  element #"E"# contain?

Cameron Andrews · Accepted Answer

#"0.3 moles"#

The first thing to notice here is that #1# mole of your unknown compound contains

Now, use the total mass of the sample and the mass of element #"E"# to calculate the mass of oxygen.

#color(blue)(ul(color(black)("mass of sample" = "mass of E" + "mass of O")))#

Plug in your values to find

#"mass of O" = "8 g" - "5.6 g" = "2.4 g"#

Use the molar mass of oxygen to calculate how many moles you have in this sample of #"E"_2"O"_3#

#2.4 color(red)(cancel(color(black)("g"))) * "1 mole O"/(16.0color(red)(cancel(color(black)("g")))) = "0.15 moles O"#

This means that the #"8-g"# sample of #"E"_2"O"_3# contains

#0.15 color(red)(cancel(color(black)("moles O"))) * "2 moles E"/(3color(red)(cancel(color(black)("moles O")))) = "0.10 moles E"#

Now, notice that you have

#(16.8 color(red)(cancel(color(black)("g E"))))/(5.6 color(red)(cancel(color(black)("g E")))) = 3#

This means that #"16.8 g"# of element #"E"# will contain three times as many moles as #"5.6 g"# of element #"E"#.

Therefore, you can say that

#color(darkgreen)(ul(color(black)("moles E in 16.8 g" = 3 xx "0.10 moles" = "0.3 moles")))#

The answer must be rounded to one significant figure.

Owen Ambrose · Answer

undefined In order to ascertain the quantity of element E present in a 16.8 g sample, we must first ascertain the molar mass of E₂O₃. Subsequently, we can compute the moles of E by applying the provided mass ratio. The molar mass of E₂O₃ is as follows: E: 5.6 g O: (8 g - 5.6 g) = 2.4 g Molar mass of E₂O₵ = 5.6 g/mol + 2.4 g/mol = 8 g/mol. This allows us to determine the moles of E present in the 16.8 g sample: Moles of E = (mass of sample) / (molar mass of E) Moles of E = 16.8 g / 8 g/mol = 2.1 moles

Axel Alvarado · Answer

undefined First, we need to find the molar mass of compound $E_2O_3$, which consists of element $E$ and oxygen ($O$).

The molar mass of $E_2O_3$ is the sum of the atomic masses of $E$ and $O$, where $E$ is present in 8 grams of $E_2O_3$ with a mass of 5.6 grams.

Given that 8 grams of $E_2O_3$ contain 5.6 grams of $E$, we can find the molar mass of $E$:

$$\text{Molar mass of } E = \frac{\text{Mass of } E}{\text{Mass of } E_2O_3} \times \text{Molar mass of } E_2O_3$$

$$\text{Molar mass of } E = \frac{5.6\, \text{g}}{8\, \text{g}} \times \text{Molar mass of } E_2O_3$$

Next, we'll use the molar mass of $E$ to find the number of moles of $E$ in a 16.8-gram sample:

$$\text{Number of moles of } E = \frac{\text{Mass of sample}}{\text{Molar mass of } E}$$

Substituting the given values:

$$\text{Number of moles of } E = \frac{16.8\, \text{g}}{\text{Molar mass of } E}$$

Now, we can solve for the number of moles of $E$ using the molar mass of $E$ calculated earlier.