Chemistry: A student mixes some water at room temperature with a white powder also at room temperature. The white powder disappears into the water, and bubbles form. The solution warms up to 30 ℃. Is this likely a physical or a chemical change? Explain your answer.

A student mixes some water at room temperature

proutyhaylee

06.10.2020

The formula for a hydrate : NiSO₄. 7H₂O

Further explanation

Given

55.2% NiSO₄, and 44.8% H₂O

Required

The formula

Solution

MW NiSO₄ = 154,75 g/mol

MW H₂O = 18 g/mol

Mol ratio :

NiSO₄ : 55.2 : 154,75 g/mol = 0.357

H₂O : 44.8 : 18 g/mol = 2.49

Divide by 0.357 :

NiSO₄ = 0.357/0.357 = 1

H₂O = 2.49/0.357 = 7

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