A solution of sodium chloride is mixed with a solution of lead(II) nitrate. A precipitate of lead(II) chloride results, leaving
1 answer:
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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.
Answer:
The empirical formula of the compound is .
Explanation:
We need to determine the empirical formula in its simplest form, where hydrogen () is scaled up to a mole, since it has the molar mass, and both carbon (
) and oxygen (
) are also scaled up in the same magnitude. The empirical formula is of the form:
Where ,
are the number of moles of the carbon and oxygen, respectively.
The scale factor (), no unit, is calculated by the following formula:
(1)
Where:
- Mass of hydrogen, in grams.
- Molar mass of hydrogen, in grams per mole.
If we know that and
, then the scale factor is:
The molar masses of carbon () and oxygen (
) are
and
, then, the respective numbers of moles are: (
,
,
)
Carbon
(2)
Oxygen
(3)
Hence, the empirical formula of the compound is .