Calcium hydride reacts with water to form calcium hydroxide and hydrogen gas. (a) Write a balanced chemical equation for the reaction.

Video transcript

Hey everyone. This question tells us that the reaction of hydrogen gas and solid chromium three oxide yields chromium metal and water vapor. They want us to determine the balanced chemical equation for the desired reaction first, let's go ahead and write out what we have. So we have hydrogen gas And we have solid chromium three oxide. So to figure this out, we know that we have chromium with a plus three charge. Since we have that Roman, numeral three denoting this. And we're combining this with oxygen with a -2 charge since it's in our group six a When we use our criss cross method, we end up with a formula of cr 203. So we have hydrogen gas plus Solid chromium three oxide and we yield chromium metal plus water vapor. So this is going to be our reaction. We can go ahead and balance this out first. Let's calculate the number of atoms we have on each side. So starting with our react inside, we have two of hydrogen, two of chromium and three of oxygen in our product side, we have two of hydrogen, one of chromium and one of oxygen. We can first balance out our oxygen's by adding a coefficient of three prior to our water in our product side. When we do this, we end up with three of oxygen and six of hydrogen. Next we can balance out our hydrogen gas by adding a coefficient of three prior to it, changing our hydrogen into six as well. Lastly we can add a coefficient of two prior to our solid chromium and this will change our chromium to two. Now that everything is balanced out, this is going to be our final balanced chemical reaction. So I hope this made sense and let us know if you have any questions.