Question

Calculate the mass in grams of each of the following substances. 6.02 x 10²³ atoms of Mg

Calculate the mass in grams of each of the following substances.
12.4 x 10¹⁵ molecules of CH₂O

Calculate the mass in grams of each of the following substances.
3.01 x 10²³ formula units of CaCl₂

Answer 1

To find the mass in grams of Mg, CH2O, and CaCl2 based on given numbers of particles, we use their respective molar masses (24.305 g/mol for Mg, 30.026 g/mol for CH2O, 110.98 g/mol for CaCl2) and convert using Avogadro's number.

Step-by-step explanation:

To calculate the mass in grams of substances based on given quantities of particles, we use the molar mass and Avogadro's number (6.02 x 10²³ particles/mol). Here's how we can compute the mass for each substance:

• Magnesium (Mg): One mole of Mg atoms has a molar mass of approximately 24.305 g/mol. Since 6.02 x 10²³ atoms of Mg is one mole, the mass is 24.305 grams.
• Formaldehyde (CH₂O): The molar mass of CH₂O, obtained by adding the atomic masses of carbon (12.01 amu), hydrogen (2 x 1.008 amu), and oxygen (16.00 amu), is approximately 30.026 g/mol. To find the mass of 12.4 x 10¹⁵ molecules, first calculate the number of moles by dividing the number of molecules by Avogadro's number. Then multiply by the molar mass.
• Calcium Chloride (CaCl₂): The molar mass is 110.98 g/mol. With 3.01 x 1023 formula units, which corresponds to 0.5 moles, we calculate the mass as the product of 0.5 moles and 110.98 g/mol.

Answer 2

The mass of each substance can be found through stoichiometric calculation as follows:


`(g)/(u) = (a)/(C)`

where "g" is the mass of substance, "u" is the relative atomic mass, "a" is the number of atoms or molecules and "C" is Avogadro's number.

Making use of that formula, we have:

a) 6.02 x 10²³ atoms of Mg.


`(g)/(24.3)= (6.02* 10^(23))/(6.02 *10^(23)) \\ \boxed {g= 24.3~g}`

b) 12.4 x 10¹⁵ molecules of CH₂O.


`(g)/(12+2 * 1+16)= (12.4* 10^(25))/(6 *10^(23)) \\ g= (30 * 12.4 * 10^(25))/(6 *10^(23)) \\ \boxed {g= 6.2~kg}`

c) 3.01 x 10²³ formula units of CaCl₂


`(g)/(40+2 * 35.5)= (3.01 * 10^(25))/(6 *10^(23)) \\ g= (111 * 3.01 * 10^(25))/(6 *10^(23)) \\ \boxed {g= 5.5685~kg}`