The formula for magnesium chlorate is Mg(ClO3)2.
You have already gotten the balanced equation. And the ratio of mol number of reactants and production is the ratio of coefficient. So there is 6.4/8*11=8.8 mol oxygen needed. The mass is 8.8*32=281.6 g.
There are 60 seconds in one minute
565900 / 60 = 9431.667 minutes in 565,900 seconds
There are 60 minutes in an hour
9431.667 minutes / 60 = 157.9144 hours in 565900 seconds
There are 24 hours in 1 day
157.9144 hours / 24 hours = 6.5498 days.
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