2KClO₃ → 2KCl + 3O₂ If 25.0 g of KClO₃ decompose, what mass of O₂ will form? *​

approximately 15.1 grams.

Explanation: The key to chemistry is to change everything to moles. Then when you have the answer in moles change the answer back to grams, liters, or whatever you want. Change 25 grams of potassium chlorate to moles. Chlorate is Cl with 3 oxygens. ate = saturated. Chlorine has seven valance electrons when it is saturated six of these electrons are used by oxygen ( 2 electrons per oxygen) leaving only 1 electron. 1 K x 39 grams/mole+1 Cl x 35.4grams/ mole+3 O x 16 grams/ mole = 122.4 grams / mole Potassium Chlorate 25 122.4 = moles. 2.05 moles of Potassium Chlorate. There is a 1:1 mole ratio. 1 mole of Potassium Chlorate will produce 1 mole of Potassium Chloride. 2.05 moles of Potassium Chlorate will produce 2.05 moles of Potassium Chloride. Find the gram molecular mass of Potassium Chloride. 1 K x 39 = 39+1 Cl x 35.4 = 35.4 = 74.4 grams / mole. 2.05 moles x 74.4 grams/ mole = 15.2 grams

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

the answer is na (sodium)