Question

Образец сплава лития и калия массой 4,6 г растворили в воде. Выделившийся водород сожгли и получили 1,8 г воды. Определите массу калия в сплаве.

Answer 1

  2x                       x
2Li+2H2O=2LiOH+H2
 2y                       y
2K+2H2O=2KOH+H2
0.1            0.1
2H2+O2=2H2O

n(H2O)=1.8/18=0.1

14x+78y=4.6
x+y=0.1

x=0.1-y

14(0.1-y)+78y=4.6
1.4-14y+78y=4.6
64y=3.2
y=0.05
x=0.05

m(K)=3.9
m(Li)=0.7

Не за что.

Answer 2

Calculation of the Mass of Potassium in the Alloy

To determine the mass of potassium in the alloy, we can use the information provided about the mass of the alloy and the mass of water produced when the hydrogen gas is burned.

Given: - Mass of the lithium and potassium alloy = 4.6 g - Mass of water produced = 1.8 g

To find the mass of potassium in the alloy, we need to subtract the mass of lithium from the total mass of the alloy. Since the alloy contains both lithium and potassium, we need to determine the mass of lithium first.

To do this, we can assume that the mass of lithium is proportional to the mass of water produced. We can set up a proportion using the masses of lithium and water:

Lithium mass / Water mass = Alloy mass / Total water mass

Let's denote the mass of lithium as *m* and the mass of potassium as *x*.

Using the given values, we have:

m / 1.8 g = 4.6 g / (1.8 g + 1.8 g)

Simplifying the equation:

m / 1.8 g = 4.6 g / 3.6 g

Cross-multiplying:

m = (4.6 g / 3.6 g) * 1.8 g

Simplifying further:

m = 2.3 g

Now that we have the mass of lithium, we can find the mass of potassium by subtracting the mass of lithium from the total mass of the alloy:

x = 4.6 g - 2.3 g

Simplifying:

x = 2.3 g

Therefore, the mass of potassium in the alloy is 2.3 g.

Conclusion

The mass of potassium in the alloy is 2.3 grams.