Answer to Question #142901 in General Chemistry for afiq

Question

The formula of organic compound is C2Hy. The mass of 2.01 x 10^23 C2Hy molecules is 10.0g. Determine value of y

Answer 1

Q142901

The formula of an organic compound is C2Hy. The mass of 2.01 x 10^23 C2Hy molecules is 10.0g. Determine the value of y.

Solution:

Step 1: We will first convert the given ‘molecules of C₂H_y‘ to ‘moles of C₂H_y.

Step 2: In this step, we find the molar mass of C₂H_y using ‘moles of C₂H_y‘ and the given grams of C₂H_y .

Step 3: In this step, we will set up the equation for molar mass of C₂H_y and find the value of y.

Step 1: Convert ‘molecules of C₂H_y‘ to ‘moles of C₂H_y.

We can use the Avagadro’s constant, 1mol = 6.022 *10²³ molecules, and convert

2.01 * 10²³ C₂H_y molecules to moles.

Moles of C₂H_y = 2.01 * 10²³ molecules of C₂H_y * 1 mol C₂H_y /6.022 * 10²³ molecules of C₂H_y

= 0.3338 moles of C₂H_y .

Step 2: Find the molar mass of C₂H_y using 0.3338 moles of C₂H_y and 10.0grams.

In question, we are told that the mass of 2.01 * 10²³ C₂H_y molecules is 10.0grams.

We know that 2.01 * 10²³ C₂H_y molecules = 0.3338moles.

So this means that the mass of 0.3338 moles of C₂H_y is 10.0grams.

We know, molar mass = grams/moles ;

molar mass of C₂H_y = 10.0grams/0.3338 moles = 29.96g/mol.

Step 3: To find the value of y.

Molar mass of C₂H_y = 2 * atomic mass of C + y * atomic mass of H. ----- Equation 1,

We know molar mass of C₂H_y = 29.96g/mol, Atomic mass of C = 12.011g/mol

and atomic mass of H = 1.00794g/mol. Substitute this in Equation 1, we have

29.96g/mol = 2* 12.011g/mol + y * 1.00794 g/mol

29.96g/mol = 24.022g/mol + y * 1.00794g/mol

Subtract 24.022g/mol from both the side we have

29.96g/mol - 24.022g/mol = 24.022g/mol + y * 1.00794g/mol – 24.022g/mol;

5.938g/mol = y * 1.00794g/mol

divide both the side by 1.00794g/mol, we have

5.938g/mol / 1.00794g/mol = y * 1.00794g/mol / 1.00794g/mol

5.891 = y ;

the nearest whole number to 5.89 is 6.

Hence the value of y is 6.