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3 years ago

Which statement best describes the properties of covalent compounds?

1 answer:

4 0

Covalent network. A solid that is extremely hard, that has a very high melting point, and that will not conduct electricity either as a solid or when molten is held together by a continuous three-dimensional network of covalent bonds. Examples include diamond, quartz (SiO 2 ), and silicon carbide (SiC). The electrons are constrained in pairs to a region on a line between the centers of pairs of atoms.

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You need to prepare 100.0 mL of a pH 4.00 buffer solution using 0.100 M benzoic acid (p K a = 4.20 ) and 0.220 M sodium benzoate

ddd [48]

Answer:

34.5 mL

Explanation:

Given, we ned to prepared buffer solution with pH = 4.00 , volume = 100.0 mL .

[C6H5COOH] = 0.100 M , [C6H5COO-] = 0.120 M , pKa = 4.20

First we need to calculate the ratio of the conjugate base and acid

We know, Henderson Hasselbalch equation

pH = pKa + log [C6H5COO-] /[C6H5COOH]

4.00 = 4.20 + log [C6H5COO-] /[C6H5COOH]

log [C6H5COO-] /[C6H5COOH] = 4.00-4.20

= - 0.20

Antilog from both side

[C6H5COO-] /[C6H5COOH] = 0.631

Now we are given the molarity of each acid and its conjugate base and we need to calculate for volume

Sum of volume = 100 mL = 0.100 L

volume of benzoic acid = x

volume of benzoate = 0.10 -x ,

so Volume of acid + volume of conjugate base = 0.100 L

[C6H5COO-] /[C6H5COOH] = 0.631

[C6H5COO-] = 0.631 * [C6H5COOH]

0.120 (0.1-x) = 0.631 *0.100x

So, x = 0.065

So, volume of benzoic acid = x = 0.0655 L

= 65.5 mL

So, volume of sodium benzoate = 0.1 -x

= 0.1-0.0655

= 0.0345 L

= 34.5 mL

So we need to mix 65.5 mL of 0.100 M benzoic acid and 34.5 mL of 0.120 M sodium benzoate form 100.0 mL of a pH=4.00 buffer solution.

5 0

3 years ago

Read 2 more answers

Given the three equations below, what is the heat of reaction for the production of glucose, C6H12O6, as described by this equat

UkoKoshka [18]

Answer:

- 1273.02 kJ.

Explanation:

This problem can be solved using Hess's Law.

Hess's Law states that regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes. This law is a manifestation that enthalpy is a state function.

We should modify the given 3 equations to obtain the proposed reaction:

6C(s) + 6H₂(g) + 3O₂(g) → C₆H₁₂O₆(s),

We should multiply the first equation by (6) and also multiply its ΔH by (6):

6C(s) + 6O₂(g) → 6CO₂(g), ∆H₁ = (6)(–393.51 kJ) = - 2361.06 kJ,

Also, we should multiply the second equation and its ΔH by (6):

6H₂(g) + 3O₂(g) → 6H₂O(l), ∆H₂ = (6)(–285.83 kJ) = - 1714.98 kJ.

Finally, we should reverse the first equation and multiply its ΔH by (- 1):

6CO₂(g) + H₂O(l) → C₆H₁₂O₆(s) + 6O₂(g), ∆H₃ = (-1)(–2803.02 kJ) = 2803.02 kJ.

By summing the three equations, we cam get the proposed reaction:

6C(s) + 6H₂(g) + 3O₂(g) → C₆H₁₂O₆(s),

And to get the heat of reaction for the production of glucose, we can sum the values of the three ∆H:

∆Hrxn = ∆H₁ + ∆H₂ + ∆H₃ = (- 2361.06 kJ) + (- 1714.98 kJ) + (2803.02 kJ) = - 1273.02 kJ.

6 0

2 years ago

Read 2 more answers

Who can do 1 for me So so so confused PLEASE help

Arturiano [62]

Draw an arrow from outside the cell (where there is only 1 water molecule) to inside that circle. Then color the water molecules that are labeled h2o:)

7 0

3 years ago

What is the quantity of heat evolved when 15g of CH4 is completely burned in air? Given that CH4+2O2→ CO2+2H2OΔH=-890Kj/mol

bagirrra123 [75]

Answer:

You're going to have to convert the grams to moles, and then multiply that with the ratio of heat produced to the ratio of CH4