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2 years ago

I NEED HELP PLSSS- 8th grade science

Chemistry

2 answers:

goblinko [34]2 years ago

8 0

Answer:

Sorry it is so blur how can l answer

maxonik [38]2 years ago

5 0

I would say E because food is chemical energy and mechanical energy is when something is moving

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Why is bronze preferred in making statue

cupoosta [38]

Bronze metal is harder and more malleable than copper. It is also conducts property of ductility, so it can be easily shaped as a statue.

6 0

2 years ago

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

2 years ago

Which of the following correctly describes what happens to the kinetic energy of water when it changes from steam to a liquid?

asambeis [7]

Answer:

The kinetic energy of the molecules increases

Explanation:

Because when the water is heated up more kinetic energy is added.

5 0

2 years ago

When you dissolve solid sugar into water, this new solution will taste sweet. the sugar went through a chemical change?

dybincka [34]

Basically the sugar breaks down until it’s eventually evaporated and spreads to different parts of the water solution and while it’s spreading the chemicals and the flavors in the sugar are going into the molecules and atoms in the water and mixing to make the water solution taste sweet just like sugar. So i would say it would be a physical change not a chemical change.

7 0

3 years ago

To determine the concentration of an EDTA solution, 4.11 g of Zn metal was used. The volume of EDTA solution needed to reach the

USPshnik [31]

Answer:

2.23M

Explanation:

Molarity of a solution is calculated thus

Molarity = number of moles (n) ÷ volume (V)

According to this question, 4.11g of Zn metal was used in order to reach a volume of EDTA solution of 28.26 mL.

28.26mL = 28.26/1000

= 0.02826L

Using mole = mass/molar mass to calculate no. of moles of Zn

Mole = 4.11/65.4

mole = 0.0628mol

Molarity = 0.0628 ÷ 0.02826

Molarity = 2.23M

The concentration of the EDTA solution used is 2.23M

7 0

2 years ago