What purpose would this particular combination of elements be used for in any human endeavor?
Bad use of elements: while barium and aluminium are elements (and at least barium is likely not to be present in elemental (metal) form), ethyl bromide is not an element, but a molecule made of the elements carbon (2), hydrogen (5), and bromineIf I was faced with this as a forensic puzzle, I'd first need to find out what chemical (and physical) form the aluminium hadAl foil is an ubiquitious packaging materialAluminium oxides and silicates are ubiquitious soil constituentsEthyl bromide doesn't occur naturallyLiquid at room temperature, will react violently with powdered aluminium (the bromine will react with the metal, and the reaction heat will ignite the organic rest of the molecule)The bromide can be used in chemical synthesisIts use as a solvent probably has been forbidden, but wouldn't have been widespread anyway because alkyl bromides and iodides decompose rapidly under sunlightBarium remains the puzzleBarium salts are used in chemical analytics, or as X-ray contrast infusionsMetallic barium is extremely unstable, in fact I haven't ever encountered it in my career as a chemist, so I will rule that outThe only guess I can give is a badly packaged or possibly sabotaged lab supply transport.
You have to make sure there is the same number of carbons, hydrogens etc on either side of the reaction/equationE.gfor Q1Both sides have 1 C, but the left side has 4 H and 2 O whilst the right hand side has 2 H and 3 OThe only way you can balance these is to put different numbers in front of the compoundsFor example, you could balance the H by putting a 2 in front of the H2O, giving you 4 H and 2 O from the water aloneBut now you have 4 O on the right hand side and only 2 O on the left hand sideluckily putting a 2 in front of the O2 will balance this out without needing to readjust anything elseFor the other questions do the same thingStart off with balancing the elements that are only in one compound on each side, for example start off with balancing the Cl in Q6.
