Answer:
A pure substance is made up of only one ingredient or combination. A mixture is made up of two or maybe more separate components that are not chemically linked.
Explanation:
Advocates for the use of hydrogen fuel cells posit that unlike other sources of power, these fuel cells do not emit harmful carbon emissions in the air that cause pollution and affect global warming. Although the chemical process involves burning hydrogen<span>, it emits water, heat and other emissions but not carbon.
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Answer: CoBr3 < K2SO4 < NH4 Cl
Justification:
1) The depression of the freezing point of a solution is a colligative property, which means that it depends on the number of particles of solute dissolved.
2) The formula for the depression of freezing point is:
ΔTf = i * Kf * m
Where i is the van't Hoof factor which accounts for the dissociation of the solute.
Kf is the freezing molal constant and only depends on the solvent
m is the molality (molal concentration).
3) Since, you are assuming equal concentrations and complete dissociation of the given solutes, the solute with more ions in the molecular formula will result in the solution with higher depression of the freezing point (lower freezing point).
4) These are the dissociations of the given solutes:
a) NH4 Cl (s) --> NH4(+)(aq) + Cl(-) (aq) => 1 mol --> 2 moles
b) Co Br3 (s) --> Co(3+) (aq) + 3Br(-)(aq) => 1 mol --> 4 moles
c) K2SO4 (s) --> 2K(+) (aq) + SO4 (2-) (aq) => 1 mol --> 3 moles
5) So, the rank of solutions by their freezing points is:
CoBr3 < K2SO4 < NH4 Cl
Answer:
Moles of 
= 6 moles
Explanation:
The reaction of 
and 
to make is:
⇒
The above reaction shows that 2 moles of Sc can react with 3 moles of to form 
Mole Ratio= 2:3
For 10 moles of Sc we need:
Moles of = 
Moles of = 
Moles of =15 moles
So 15 moles of are required to react with 10 moles of but we have 9 moles of , it means is limiting reactant.
Moles of ScCl_3= 6 moles
Answer:
Released
Explanation:
When particles that attract each other come together, energy is usually released. The combination of the two particles is expected to result in a lower energy system. This lower energy system will be more stable than the different individual particles.
Hence, as this lower energy system is formed, the excess energy originally possessed by the particles is evolved hence energy is released when particles that attract each other are allowed to come together.
