Well, if it was 40 grams of NaOH and 36.5 grams of HCl, then you would have 18 grams of water and 58.5 grams of NaCl. With 1g HCl to .5g NaOH, well, you have an acidic, salty, mess. However, HCl is a gas at STP, and NaOH is a solid...
Basically, it's an incredibly poorly worded question.
It looks like the original poster grabbed two of the simplest acids and bases he could find and plugged them into the question. HCl is usually provided in an aqueous solution. NaOH is a solid. In those two states they'll combine quite well with each other. The "explosion and a big mess" would come from somebody just chucking a lot of both chemicals together without any regard what is going on. I think Anonymous was more interested in what products were produced and how much of each were produced, and then made the mistake of assuming that the chemist had enough brains not to go chuck two reactive chemicals together without the competence to run through the necessary calculations. Throwing together any amount of any chemicals without knowing what you're doing is a very bad idea. It's a good way to "accidentally" produce chlorine gas, carbon monoxide, or worse. If you don't know what you're doing or you aren't at least minimally competent and take appropriate safety precautions, keep it on paper. Personally, I steer clear of college and high school chemistry labs for this reason. I watched some idiot produce chlorine gas back in high school, though thankfully not in any really, really dangerous quantities. NaOH + HCl ---> NaCl + H O 2 It's a nice, simple reaction. To answer the question the student would have to know the atomic masses of chlorine, hydrogen, oxygen, and sodium, but that could easily be gleaned off a periodic table provided the student was competent enough to ask for one if he needed it. I doubt most college chemistry professors would analyze it that well either, to tell you the truth. They'd give the question and it's assumed that the necessary steps are taken to ensure a reaction (if any). Of course "normal circumstances" is kind of a wide area. The question should have been worded more like this: 11) Michelle mixes one gram of HCl and one half gram of NaOH. The HCl is dissolved in water. Assuming that Michelle is competent enough to avoid blowing herself across the room or destroying the lab, what are the products and in what quantities are they produced?