During a lab, you heat 1.62 g of a CoCl2 hydrate over a Bunsen burner. After heating, the final mass of the dehydrated compound
is 0.88 g. Determine the formula of the hydrate and also give the full name of the hydrate. Please show all your work for the calculations for full credit.
Let the number of moles of water in the required formula be "y". The final formula should be in the form of : CoCl2 yH2O 1.62 g is the weight of CoCl2 and water in the sample After heating, the remaining mass represents the mass the salt only mass of water in sample = 1.62 - 0.88 = 0.74 g
From the periodic table: molar mass of cobalt is 59 g molar mass of chlorine is 35.5 molar mass of hydrogen is 1 molar mass of oxygen is 16
molar mass of formula = 59 + 2(35.5) + 18y = 130 + 18y g Now we have calculate the mass/molar mass for each part of the formula (salt and water) and equate them to get number of moles of water as follows: 0.88 / 130 = 0.74 / y18 <span>y = 6.07 which is approximately 6 moles </span> Thus, the final formula is CoCl2 6H2O. This hydrate is called cobalt(II)<span>chloride hexahydrate.</span>
It is +5. There -8 charge due to four oxygen atoms and +3 due to one sodium atom and 2 hydrogen atom which makes it necessary for phosphorus to have +5 charge on it to make the compound electrically neutral. The charge on phosphorus corresponds to its oxidation number.
Graduated cylinders are designed for accurate measurements of liquids with a much smaller error than beakers. They are thinner than a beaker, have many more graduation marks, and are designed to be within 0.5-1% error. ... Therefore, this more precise relative of the beaker is just as critical to almost every laboratory.
