Answer:
Mass = 0.610 g
Explanation:
Given data:
Mass of Na₂SiO₃ = ?
Mass of HF = 0.800 g
Solution:
Chemical equation:
Na₂SiO₃ + 8HF → H₂SiF₆ + 2NaF + 3H₂O
Number of moles of HF:
Number of moles = mass/ molar mass
Number of moles = 0.800 g/ 20 g/mol
Number of moles = 0.04 mol
Now we will compare the moles of HF and Na₂SiO₃.
HF : Na₂SiO₃
8 : 1
0.04 : 1//8×0.04 = 0.005
Mass of Na₂SiO₃:
Mass = number of moles × molar mass
Mass = 0.005 mol × 122.07 g/mol
Mass = 0.610 g
(2) U-238 is the radioisotope used in dating geological formations. Uranium-238 has a half-life of 4.46 billion years, which makes it suitable to date such old formations.
The other options do not have such long durabilities and half-lives.
