Final answer:
To find the mass of NH₄Cl, the mass of NaCl and SiO₂ is subtracted from the total mass of the mixture. The mass of NH₄Cl is found to be 2.3731 g.
Step-by-step explanation:
To determine the mass of NH₄Cl, we need to use the data provided.
The initial mass of the mixture is given as 10.0511 g. After the NaCl and SiO₂ have been accounted for, the mass of the dish plus these two substances is 76.8256 g. Deducting the mass of the empty evaporating dish (69.1476 g) from this amount gives the combined mass of NaCl and SiO₂ as 7.6780 g (76.8256 g - 69.1476 g).
Now, we subtract the mass of NaCl and SiO₂ from the initial mass of the mixture to find the mass of NH₄Cl: 10.0511 g - 7.6780 g = 2.3731 g. Therefore, the mass of NH₄Cl in the mixture is 2.3731 g.