Answer:
Investigation B, Step 2
Explanation:
The <em>colour change</em> is a good indication of a <em>chemical change</em>. The sugar molecules were most likely changing into something else.
Investigation A, Step 1. <em>Wron</em>g. The dissolving of salt is a <em>physica</em>l process.
Investigation A, Step 2. <em>Wrong</em>. You simply boiled off the water (a <em>physical</em> process) and recovered the salt.
Investigation B, Step 1. <em>Wrong</em>. The dissolving of sugar is a <em>physical</em> process.
2 Al + 6 HCl → 2 AlCl₃ + 3 H₂ (single displacement)
Ca + Br₂ → CaBr₂ (synthesis)
4 NH₃ + 5 O₂ → 4 NO + 6 H₂O (combustion)
2 NaCl → 2 Na + Cl₂ (decomposition)
FeS + 2 HCl → FeCl₂ + H₂S (double displacement)
single displacement - is a chemical reaction of the following type: A + BC → AC + B
double displacement - is a chemical reaction of the following type: AB + CD → AC + BD
synthesis - the chemical product is obtained by combining in a synthesis the constituent elements
combustion - usually a exothermic reaction of a particular compound with oxygen
decomposition - degradation of a compound in simpler elements
Use Raoult's Law:
Psolution = (χsolvent) (P°solvent)
24.90 = (x) (25.756)
x = 0.966765 (this is the solvent mole fraction)
χsolute = 1 - 0.966765 = 0.033235
χsolute = 0.03324 (to four sig figs)
You must remember that oxidation number of hydrogen in acids is always +1, oxidation number of oxygen in oxides & acids is always -2... metals has always oxidation number on plus!
group NO3 comes from HNO3...and oxidation number of whole acid group is always on minus and equal to the amount of hydrogen atoms in this acid... so oxidation number of NO3 = -1
we have 2 NO3 groups so 2*(-1) = -2 and that is the reason why oxidation number of Fe in this formula must be +2... because sum of all elements always gives 0!
Now we could count of oxidation number for nitrogen... we write HNO3 and start counting from right to left:
3*(-2) from oxygens + 1 from hydrogen = -5
so nitrogen must have +5 oxidation number... because sum all in formula must be 0.
