Atomic mass W = 183.84 u.m.a
183.84 g ----------- 6.02x10²⁴ atoms
?? g ---------------- 2.1x10²⁴ atoms
2.1x10²⁴ x 183.84 / 6.02x10²⁴ =
3.860x10²⁶ / 6.02x10²⁴ = 641.30 g
hope this helps!
Answer:

Explanation:
10.11 g sample of
contains 22.34%
by mass
According to the law of constant composition the if one sample of
has 22.34% of
by mass then any other sample of
will have the same percentage of the amount of
.
For a sample of 7.09 g we have

The mass of sodium in the required sample is
.
Answer:
To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter (molarity). The pH is then calculated using the expression: pH = - log [H3O+].
Example: Find the pH of a 0.0025 M HCl solution.