Question

Cиликат натрия получают сплавлением гидроксида натрия (NaOH) с песком. Из 25 кг песка было получено 48,8 кг силиката натрия. Вычислите процентное содержание оксида кремния (SiO2) в песке

Answer 1

2NaOH+SiO2---Na2SiO3+H2O N(Na2SiO3)=48.8/(23*2+28+48)=0.4 моль N(SiO2)=N(Na2SiO3)= 0.4 моль m(SiO2)=0.4*(32+28)=24 г W=24/25*100%=96% Ответ: 96%

Answer 2

Calculation of the Percentage of Silicon Dioxide (SiO2) in Sand

To calculate the percentage of silicon dioxide (SiO2) in sand, we need to know the amount of SiO2 present in the obtained sodium silicate and the initial weight of the sand.

Given: - Weight of sand = 25 kg - Weight of sodium silicate obtained = 48.8 kg

To find the weight of SiO2 in the obtained sodium silicate, we can use the following equation:

Weight of SiO2 = Weight of sodium silicate - Weight of Na2O

The molar ratio of SiO2 to Na2O in sodium silicate is 1:2. Therefore, the weight of Na2O can be calculated as follows:

Weight of Na2O = (Weight of sodium silicate / 3) * 2

Now, we can calculate the weight of SiO2:

Weight of SiO2 = Weight of sodium silicate - Weight of Na2O

Finally, we can calculate the percentage of SiO2 in sand:

Percentage of SiO2 in sand = (Weight of SiO2 / Weight of sand) * 100

Let's perform the calculations:

Weight of Na2O = (48.8 kg / 3) * 2 = 32.53 kg

Weight of SiO2 = 48.8 kg - 32.53 kg = 16.27 kg

Percentage of SiO2 in sand = (16.27 kg / 25 kg) * 100 = 65.08%

Therefore, the percentage of SiO2 in the sand is approximately 65.08%.

Please note that the calculations provided above are based on the given information and assumptions.