Question

Calculate the mass of hydrogen formed when 25 grams of aluminum reacts with excess hydrochloric acid. 2Al + 6HCl --> Al2Cl6 + 3H2. Show your working. (Relative atomic masses: H, 1.0; Al, 27.0; Cl, 35.5)

Answer 1

The mass of hydrogen formed when 25 grams of aluminum reacts with excess hydrochloric acid is 2.78 gram.

- The reaction is given as:

2Al + 6HCl --> Al2Cl6 + 3H2

- According to the given reaction, we have

Mass of hydrogen formed by 54 gm Al = 6 gram

⇒ Mass of hydrogen formed by 1 gm Al = 6/54 gram = 1/9 gram

⇒ Mass of hydrogen formed by 25 gm Al = (1/9) × 25 gram = 2.78 gram.

Answer 2

Given: 25gAl

Recquired: Mass of hydrogen (H)

Solution:  gA --> molA --> molB --> gB

2Al + 6HCl --> $Al_{2}$$Cl_{6}$ + 3$H_{2}$

molar mass of Al = 26.98gAl

molar mass of $H_{2}$ =2.01588g$H_{2}$

$\frac{25gAl}{1} x \frac{1molAl}{26.98gAl} x \frac{3molH_{2}}{2molAl} x \frac{2.01588gH_{2}}{1molH_{2}} =2.801908821gH_{2} ->\frac{2.801908821gH_{2}}{2} =1.401gH$

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