Water decomposes to make 4g of hydrogen gas & 32g of oxygen gas. What mass of water decomposed? How do u know?

It would be 36 grams, because mass is conserved. If 36 came out, 36 must have gone in.

Ok

The decomposition of water into gases is

2H2O ---> 2H2 + O2

OK from convention of mass

4g + 32g = 36g

now (I'm cheating a bit here)

lets sub these values into the equation with 32 g = H2O

4g = H2 and 36 g = O2

this comes to

4g(H2) + 32 g (O2) ----> 36 g (H2O)

How lets divide each compound by its molecular mass

H2 = 2 g, O2 = 32 g and water 18 g

The equation becomes.

2H2 + O2 ----> 2H2O

Now this equation is similar to the first one at the top. If it was not that would mean eitherr your experiment data is faultily or there was another compound decomping as well.

dear know thou. just law of mass conversation,. this is 36 gram of water. (Dr. rakesh sharma...sahil studyn circle)