Calculate the mass of a sample of cobalt containing 3.31x10^22 atoms

Mass = 3.24 g

Explanation:

Given data:

Number of atoms of cobalt = 3.31 × 10²² atoms

Mass of cobalt = ?

Solution:

We will calculate the number of moles of cobalt first.

1 mole contain 6.022× 10²³ atoms

3.31 × 10²² atoms  × 1 mol / 6.022× 10²³ atoms

0.0549 mol

Mass of cobalt:

Mass = number of moles × molar mass

Mass = 0.0549 mol × 58.93 g/mol

Mass = 3.24 g

in the given question, the partial pressure is calculated by using the ideal gas equation, that is, pv = nrt

here, p is pressure, v is volume = 25 l, n is number of moles = 0.0104 moles, r is gas constant = -0.0821 l.atm / mol.k

t is temperature = 273 k

p = nrt / v

p = (0.0104 mol × 0.0821 l.atm / mol.k × 273 k) / 25 l

= 0.0093 atm

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.