Answer:
- Question 19: the three are molecular compounds.
Explanation:
<em>Question 19.</em>
All of them are the combination of two kinds of different atoms in fixed proportions.
- C₂H₄: two carbon atoms per four hydrogen atoms
- HF: one hydrogen atom per one fluorine atom
- H₂O₂: two hydrogen atoms per two oxygent atoms
Thus, they all meet the definition of compund: a pure substance formed by two or more different elements with a definite composition.
Molecular compounds are formed by covalent bonds and ionic compounds are formed by ionic bonds.
Two non-metal elements, like H-F, C - C, C - H, H-O, H - H, and O - O will share electrons forming covalent bonds to complete their valence shell. Thus, the three compounds are molecular and not ionic.
<em>Question 20. </em>Formula of copper(II) sulfate hydrate with 36.0% water.
Copper(II) sulfate is CuSO₄. Its molar mass is 159.609g/mol
Water is H₂O. Its molar mass is 18.015g/mol
Calling x the number of water molecules in the hydrate, the percentage of water is:

From which we can solve for x:

Thus, there are 5 molecules of water per each unit of CuSO₄, and the formula is:
Explanation:
The given data is as follows.
P = 3 atm
=
= 
= 9 L =
(as 1 L = 0.001
),
= 15 L = 
Heat energy = 800 J
As relation between work, pressure and change in volume is as follows.
W = 
or, W = 
Therefore, putting the given values into the above formula as follows.
W = 
= 
= 1823.85 Nm
or, = 1823.85 J
As internal energy of the gas
is as follows.
= Q - W
= 800 J - 1823.85 J
= -1023.85 J
Thus, we can conclude that the internal energy change of the given gas is -1023.85 J.
Answer:
A. 2Na + 2H₂O → 2NaOH + H₂
Explanation:
When sodium is reacted with water, a single replacement reaction occurs. The product of the reaction is typically sodium hydroxide and hydrogen gas.
Reactants:
Sodium + water
Product:
Sodium hydroxide + hydrogen gas
So;
2Na + 2H₂O → 2NaOH + H₂
Answer:
The percent composition of fluorine is 65.67%
Explanation:
Percent Composition is a measure of the amount of mass an element occupies in a compound. It is measured in percentage of mass.
That is, the percentage composition is the percentage by mass of each of the elements present in a compound.
The calculation of the percentage composition of an element is made by:

In this case, the percent composition of fluorine is:

percent composition of fluorine= 65.67%
<u><em>The percent composition of fluorine is 65.67%</em></u>
Answer: b suspension
a suspension is a heterogeneous mixture that contains solid particles sufficiently large for sedimentation . The particles may be
visible to the naked eye, usually must be larger than one micrometer , and will eventually settle, although the mixture is only classified as a suspension when and while the particles have not settled out. A suspension is a heterogeneous mixture in which the solute particles do not dissolve , but get suspended throughout the bulk of the solvent , left floating around freely in the medium. [1] The internal phase (solid) is dispersed throughout the external phase (fluid) through mechanical agitation , with the use of certain excipients or suspending agents.
An example of a suspension would be sand in water. The suspended particles are visible under a
microscope and will settle over time if left undisturbed. This distinguishes a suspension from a colloid , in which the suspended particles are smaller and do not settle.
Colloids and suspensions are different from
solution , in which the dissolved substance (solute) does not exist as a solid, and solvent and solute are homogeneously mixed.