Question

Обчисліть: а) масу, б)кількість речовини сірки, в)число молекул що, прореагували з алюмінієм, якщо при цьому утворилося 30г алюміній сульфіду? Визначте індекси за відомими значеннями валентності Al(3)S(2). Чому дорівнює формульна маса цієї сполуки?

Answer 1

       ?                 0,2 моль

4Al + 3S2   →     2Al2S3

     3 моль         2 моль

а) масу

m(Al2S3)=30г - за умовою

M(Al2S3)=150 г/моль

n(Al2S3)=m(Al2S3)/M(Al2S3)=30/150=0,2 моль

m(S2)=n*M=0,2*64=12,8 г

б)кількість речовини сірки

n=m/M

n(S2)=12,8/64=0,2 моль

в)число молекул що, прореагували з алюмінієм

N=n*NA

N(S2)=0,2 *6,02*10^23=1,204*10^23

Визначте індекси за відомими значеннями валентності Al(3)S(2)

Al2S3

Чому дорівнює формульна маса цієї сполуки?

M(Al2S3)=27*2+32*3=150 г/моль

Answer 2

Calculation of Mass, Amount of Substance, and Number of Molecules

To calculate the mass, amount of substance, and number of molecules, we need to use the given information that 30g of aluminum sulfide (Al2S3) is formed when aluminum reacts with sulfur.

a) Mass of Aluminum (Al): - The molar mass of aluminum (Al) is 26.98 g/mol [[1]]. - Since 30g of aluminum sulfide (Al2S3) is formed, we can assume that the mass of aluminum is equal to the mass of aluminum sulfide. - Therefore, the mass of aluminum is 30g.

b) Amount of Substance of Sulfur (S): - The molar mass of sulfur (S) is 32.06 g/mol [[2]]. - Since aluminum sulfide (Al2S3) has a 2:3 ratio of aluminum to sulfur, we can calculate the amount of substance of sulfur using the mass of aluminum sulfide. - The molar ratio of aluminum to sulfur in aluminum sulfide is 2:3. - The molar mass of aluminum sulfide (Al2S3) can be calculated as follows: - Molar mass of aluminum sulfide (Al2S3) = (2 * molar mass of aluminum) + (3 * molar mass of sulfur) - Molar mass of aluminum sulfide (Al2S3) = (2 * 26.98 g/mol) + (3 * 32.06 g/mol) = 150.16 g/mol [[3]]. - Using the molar mass of aluminum sulfide, we can calculate the amount of substance of sulfur: - Amount of substance of sulfur (S) = Mass of aluminum sulfide (Al2S3) / Molar mass of aluminum sulfide (Al2S3) - Amount of substance of sulfur (S) = 30g / 150.16 g/mol = 0.1998 mol.

c) Number of Molecules that Reacted with Aluminum: - To calculate the number of molecules that reacted with aluminum, we need to use Avogadro's number, which is approximately 6.022 x 10^23 molecules/mol. - The molar ratio of aluminum to sulfur in aluminum sulfide is 2:3. - From the given information, we know that 30g of aluminum sulfide is formed. - Using the molar mass of aluminum sulfide, we can calculate the amount of substance of aluminum sulfide: - Amount of substance of aluminum sulfide (Al2S3) = Mass of aluminum sulfide (Al2S3) / Molar mass of aluminum sulfide (Al2S3) - Amount of substance of aluminum sulfide (Al2S3) = 30g / 150.16 g/mol = 0.1998 mol. - Since the molar ratio of aluminum to sulfur in aluminum sulfide is 2:3, we can calculate the amount of substance of aluminum: - Amount of substance of aluminum (Al) = (2/3) * Amount of substance of aluminum sulfide (Al2S3) - Amount of substance of aluminum (Al) = (2/3) * 0.1998 mol = 0.1332 mol. - Finally, we can calculate the number of molecules that reacted with aluminum: - Number of molecules that reacted with aluminum = Amount of substance of aluminum (Al) * Avogadro's number - Number of molecules that reacted with aluminum = 0.1332 mol * 6.022 x 10^23 molecules/mol = 8.015 x 10^22 molecules.

Valency Indices and Formula Mass

The valency indices for aluminum (Al) and sulfur (S) in aluminum sulfide (Al2S3) are Al(3)S(2).

- The valency index for aluminum (Al) is 3, which means that aluminum can form three bonds with other elements. - The valency index for sulfur (S) is 2, which means that sulfur can form two bonds with other elements.

The formula mass of aluminum sulfide (Al2S3) can be calculated by adding the atomic masses of aluminum and sulfur in the compound.

- The atomic mass of aluminum (Al) is 26.98 g/mol [[1]]. - The atomic mass of sulfur (S) is 32.06 g/mol [[2]].

Using the valency indices and atomic masses, we can calculate the formula mass of aluminum sulfide (Al2S3):

- Formula mass of aluminum sulfide (Al2S3) = (2 * atomic mass of aluminum) + (3 * atomic mass of sulfur) - Formula mass of aluminum sulfide (Al2S3) = (2 * 26.98 g/mol) + (3 * 32.06 g/mol) = 150.16 g/mol.

Therefore, the formula mass of aluminum sulfide (Al2S3) is 150.16 g/mol.

I hope this helps! Let me know if you have any further questions.

[[1]] Source: [Periodic Table - Aluminum](https://www.ptable.com/?lang=en#Properties/Atomic%20Mass) [[2]] Source: [Periodic Table - Sulfur](https://www.ptable.com/?lang=en#Properties/Atomic%20Mass) [[3]] Source: [Chemical Formula Calculator](https://www.webqc.org/molecular-weight-of-Al2S3.html)