Does adding chromium and sulfuric acid together make a reaction? What about aluminum bromide and magnesium?
Cr is high enough in the activity series that it will displace hydrogen ion from the acid. Mg metal is above Al in the activity series; therefore, Mg metal will displace aluminum ion from AlBr3.
Here is a site that gives the activity series.
http://en.wikipedia.org/wiki/Reactivity_series
To determine if a reaction occurs between two substances, we need to consider the reactivity of those substances. In the case of chromium and sulfuric acid, a reaction does not occur readily because chromium is a relatively unreactive metal and its oxide layer acts as a protective barrier.
However, if you want to confirm this with certainty, you can consult a chemical reactivity chart or refer to a database that provides information on chemical reactions. One such resource is the CRC Handbook of Chemistry and Physics, which contains a vast amount of data on chemical and physical properties.
Regarding aluminum bromide and magnesium, a reaction can indeed occur between them. Aluminum bromide is an ionic compound, and when it reacts with magnesium, a double displacement reaction occurs, resulting in the formation of magnesium bromide and aluminum metal.
To get specific information about this reaction, you can consult various sources such as chemistry textbooks, online databases, or chemical reaction calculators. These resources can provide detailed reactions along with the conditions required for the reaction to take place (e.g., temperature, pressure, and catalysts if necessary).