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3 years ago

Why do covalent compounds tend to have lower melting points than ionic compounds?

2 answers:

6 0

Because ionic compounds' strong bonds form network structures, which have a stronger attraction than the covalent compounds which are molecules.

Advocard [28]3 years ago

4 0

Simple molecular substances consist of molecules in which the atoms are joined by strong covalent bonds. Their molecules are held together by weak forces, so these substances have low melting and boiling points. ... They have high melting and boiling points.

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You have just isolated a new radioactive element. If you can determine its half-life, you will win the Nobel Prize in physics. Y

lbvjy [14]

Answer: 2.58 days

Explanation:

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = ?

t = age of sample = 6 days

a = initial amount of the reactant = 1 g

a - x = amount left after decay process = 0.2 g

a) to find the rate constant

$6=\frac{2.303}{k}\log\frac{1.0}{0.2}$

$k=\frac{2.303}{6}\log\frac{1.0}{0.2}$

$k=0.268days^{-1}$

b) for completion of half life:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

$t_{\frac{1}{2}}=\frac{0.693}{k}$

$t_{\frac{1}{2}}=\frac{0.693}{0.268}=2.58days$

The half life is 2.58 days

3 0

3 years ago

Is one mole of zinc the same as one atom of zinc?

Papessa [141]

Answer: No.

Explanation: One mole of zinc is not the same as one atom of zinc. In one mole of zinc, there are approximately 6.022*10^23 atoms of zinc.

3 0

3 years ago

How many moles of nacl are required to make 250 ml of a 3.00 m solution?

choli [55]

The molarity is calculated using the following rule:
molarity = number of moles of solvent / volume of solution (in liters)

We have the volume of solution = 250 ml = 0.25 liters and the molarity = 3 m

Substituting in the equation, we get:
3 = number of moles / 0.25
number of moles = 3 x 0.25 = 0.75 moles

4 0

3 years ago

Please please help me with this chemistry question over limiting reactants it’s due by midnight! I’ll mark you BRAINIEST!!!

OverLord2011 [107]

Answer: 1.5 moles

Explanation: one mole Zn uses 2 moles HCl.

1.5 moles Zn uses 3.0 mol HCl. Then Zn is a limiting reactant

And produces equal amount of H2.

4 0

3 years ago

The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is

Kay [80]

Answer: The Lattice energy is the energy required to separate an ionic solid into its component gaseous ions or

It is the energy released when gaseous ions combine to form an ionic solid.

Explanation:

The lattice energy depends on the ionization energies and electron affinities of atoms involved in the formation of the compound. The ionization energies and electron affinities also depends on the ionic radius and charges of the ions involved. As the ionic radius for cations increases down the groups, ionization energy decreases, whereas, as ionic radii decreases across the periods , ionization energy increases. The trend observed for anions is that as ionic radii increase down the groups, electron affinity decreases. Across the period, as ionic radii increases electron affinity increases. Also, as the charge on the ion increases, it leads to an increase in energy requirement/content.

Therefore, for compounds formed from cations and anions in the same period, the highest charged cation and anion will have the highest lattice energy. For example, among the following compounds: Al2O3 (aluminium oxide), AlCl3 (aluminium chloride), MgO, MgCl2 (magnesium chloride), NaCl, Na2O (sodium oxide); Al2O3(aluminium oxide) will have the highest lattice energy, thus will be hardest to break apart because its ions have the highest charge.

5 0

3 years ago