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erastova [34]
3 years ago
9

One afternoon, a man painted his house brown. Two days later, however, the house caught fire and burned down. What two changes o

ccurred to the house?
The painting was a physical change and the burning was a chemical change

Both painting and burning were physical changes

Neither physical nor chemical changes occurred

The painting was a chemical change and the burning was a physical change
Chemistry
1 answer:
vladimir1956 [14]3 years ago
6 0

Answer:

like my answer...........

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If 21.00 mL of a 0.68 M solution of C6H5NH2 required 6.60 mL of the strong acid to completely neutralize the solution, what was
Andru [333]

Answer:

pH = 2.46

Explanation:

Hello there!

In this case, since this neutralization reaction may be assumed to occur in a 1:1 mole ratio between the base and the strong acid, it is possible to write the following moles and volume-concentrations relationship for the equivalence point:

n_{acid}=n_{base}=n_{salt}

Whereas the moles of the salt are computed as shown below:

n_{salt}=0.021L*0.68mol/L=0.01428mol

So we can divide those moles by the total volume (0.021L+0.0066L=0.0276L) to obtain the concentration of the final salt:

[salt]=0.01428mol/0.0276L=0.517M

Now, we need to keep in mind that this is an acidic salt since the base is weak and the acid strong, so the determinant ionization is:

C_6H_5NH_3^++H_2O\rightleftharpoons  C_6H_5NH_2+H_3O^+

Whose equilibrium expression is:

Ka=\frac{[C_6H_5NH_2][H_3O^+]}{C_6H_5NH_3^+}

Now, since the Kb of C6H5NH2 is 4.3 x 10^-10, its Ka is 2.326x10^-5 (Kw/Kb), we can also write:

2.326x10^{-5}=\frac{x^2}{0.517M}

Whereas x is:

x=\sqrt{0.517*2.326x10^{-5}}\\\\x=3.47x10^-3

Which also equals the concentration of hydrogen ions; therefore, the pH at the equivalence point is:

pH=-log(3.47x10^{-3})\\\\pH=2.46

Regards!

6 0
3 years ago
When you have a free metal ion, how do the energies of these orbitals relate to one another (are they the same, different, etc.)
7nadin3 [17]

Answer:

The energy of the orbitals are the same

Explanation:

For a free metal ion, all the d-orbitals are of the same energy. The five d-orbitals are said to be five fold degenerate in the free metal ion. Hence all the d-orbitals will possess the same energy irrespective of which one is first filled.

In an octahedral or tetrahedral crystal field, the d-orbitals will loose their degeneracy and become different in energy based on their orientation towards the ligands.

4 0
4 years ago
On July 8th, I will be 8.51472x10^8 seconds old. How old will I be in years? (Assume 365 days in a year.) Group of answer choice
KatRina [158]

Answer:

26.98

almost 27 years

5 0
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Write a hypothesis about the effect of the red light on the population. Use the "if . . . then . . . because . . ." format, and
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Answer:

If the color of the light in the environment changes, then the number of light red kidney beans increases because the red light makes the light red kidney beans more difficult to see.

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