Answer: B.) I, II, and III
Explanation:
Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and
for the reaction comes out to be negative.
Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and
for the reaction comes out to be positive.
I) The temperature (of water) increases when calcium chloride dissolves in water : Thus the reaction is exothermic and
for the reaction comes out to be negative.
II) Steam condenses to liquid water : The energy is released when bonds are formed when it coverts from gas to liquid and thus
for the reaction comes out to be negative.
III) Water freezes : The energy is released when bonds are formed to get converted from liquid to solid and thus
for the reaction comes out to be negative.
IV) Dry ice sublimes : The energy is absorbed when bonds are broken to get converted from solid to gas and thus
for the reaction comes out to be positive.
If a hypothesis is not contradicted after a lot of testing it may be considered a law
The grams of Fe₂O₃ that are formed is 47.68 g
<u><em>calculation</em></u>
Step 1: write the equation for reaction
4 Fe +3O₂ → 2 Fe₂O₃
Step 2: find the moles of Fe
moles = mass÷ molar mass
= 33.4 g÷55.8 g/mol =0.5986 moles
Step 3 : use the mole ratio to determine the moles of Fe₂O₃
That is from equation above Fe:Fe₂O₃ is 4:2 therefore the moles of Fe₂O₃ is = 0.5986 moles x 2/4 =0.2993 moles
Step 4 : find the mass of Fe₂O₃
mass = mass x molar mass
The molar mass of Fe₂O₃ = (55.8 x 2 +(15.9 x3) = 159.3 g/mol
mass is therefore = 0.2993 moles x 159.3 g/mol =47.68 g