A hydrate of CoCl2 has a mass of 15.80 g before heating. After heating the mass of the anhydrous compound is found to be 9.32 g explain how you would determine the formula of the hydrate and then write out the full name of the hydrate

Explanation:

Molar mass of Cobalt (II) chloride = 129.8g/mol

Moles of CoCl2 = 9.32/129.8 = 0.0718mol

Mass of H2O lost after heating = 15.80 - 9.32 = 6.48g

Moles of H2O = 6.48/18 = 0.36mol

Mole ratio of CoCl2 : H20

= 0.0718mol : 0.36mol

= 1 : 5

Hence the formula is CoCl2 . 5H2O, which is Copper (II) chloride pentahydrate.

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

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.