The reaction 2Fe + 3Br2 ———> 2FeBr3 is an example of which type of reaction

What is the temperature increase of 6.4 kg of water when it is heated by a 7.7

lianna [129]

If you measure my hairline you will get about 90°

3 0

2 years ago

How many atoms in the pictured molecule can form hydrogen bonds with water molecules?

ddd [48]

Answer:

3

Explanation:

Please, find the image with the pictured molecule for this question attached.

The molecule has one oxygen atom (red) covalently bonded to one hydrogen atom (light grey), one nitrogen atom (blue) covalently bonded to two hydrogen atoms (light grey), and two carbon atoms (dark grey) bonded each to two hydrogen atoms (light grey).

Hydrogen bondings are intermolecular bonds (bonds between atoms of two different molecules not between atoms of the same molecule). The hydrogen bonds are attractions between the positive end of one hydrogen atom and the negative end of a small atom of other molecule (N, O, or F).

Since, nitrogen and oxygen are much more electronegative than hydrogen atoms, you conclude that:

The two hydrogen atoms covalently bonded to the nitrogen atoms have considerably partial positive charge.

The hydrogen atom covalently bonded to the oxygen atom also has a a relative large partial positive charge.

So, those are three ends of the molecule that can form hydrogen bonds with water molecules.

The hydrogen bondings are only possible when hydrogen is covalently bonded to N, O or F atoms.

4 0

3 years ago

Which of these salts is insoluble in water?

egoroff_w [7]

Answer:

2

Explanation:

3 0

3 years ago

i want to find the volume of a block of wood it has a length of 6 inches a width of 7 inces and a height of 8 inches what is the

JulijaS [17]

Answer:

336

Explanation:

L x w x h= 6 x 7 x 8 = 336

8 0

3 years ago

1. Calculate the concentration of hydronium ion of both buffer solutions at their starting pHs. Calculate the moles of hydronium

lilavasa [31]

Answer:

This question is incomplete, here's the complete question:

1. Calculate the concentration of hydronium ion of both buffer solutions at their starting pHs. Calculate the moles of hydronium ion present in 20.0 mL of each buffer.

Buffer A

Mass of sodium acetate used: 0.3730 g

Actual ph of the buffer 5.27

volume of the buffer used in buffer capacity titration 20.0 mL

Concentration of standardized NaOH 0.100M

moles of Naoh needed to change the ph by 1 unit for the buffer 0.00095mol

the buffer capacity 0.0475 M

Buffer B

Mass of sodium acetate used 1.12 g

Actual pH of the buffer 5.34

Volume of the buffer used in buffer capacity titration 20.0 mL

Concentration if standardized NaOH 0.100 M

moles of Naoh needed to change the ph by 1 unit 0.0019 mol

the buffer capacity 0.095 M

2.) A change of pH by 1 unit means a change in hydronium ion concentration by a factor of 10. Calculate the number of moles of NaOH that would theoretically be needed to decrease the moles of hydronium you calculated in #1 by a factor of 10 for each buffer. Are there any differences between your experimental results and the theoretical calculation?

3.) which buffer had a higher buffer capacity? Why?

Explanation:

Formula,

moles = grams/molar mass

molarity = moles/L of solution

1. Buffer A

molarity of NaC2H3O2 = 0.3731 g/82.03 g/mol x 0.02 L = 0.23 M

molarity of HC2H3O2 = 0. 1 M

Initial pH

pH = pKa + log(base/acid)

= 4.74 + log(0.23/0.1)

= 5.10

pH = -log[H3O+]

[H3O+] = 7.91 x 10^-6 M

In 20 ml buffer,

moles of H3O+ = 7.91 x 10^-6 M x 0.02 L

= 1.58 x 10^-7 mol

Buffer B

molarity of NaC2H3O2 = 1.12 g/82.03 g/mol x 0.02 L = 0.68 M

molarity of HC2H3O2 = 0.3 M

Initial pH

pH = pKa + log(base/acid)

= 4.74 + log(0.68/0.3)

= 5.10

pH = -log[H3O+]

[H3O+] = 7.91 x 10^-6 M

In 20 ml buffer,

moles of H3O+ = 7.91 x 10^-6 M x 0.02 L

= 1.58 x 10^-7 mol

2. let x moles of NaOH is added,

Buffer A,

pH = 5.10

[H3O+] = 7.91 x 10^-6 M

new pH = 4.10

new [H3O+] = 7.91 x 10^-5 M

moles of NaOH to be added = (7.91 x 10^-5 - 7.91 x 10^-6) x 0.02 L

= 1.42 x 10^-6 mol

3. Buffer B with greater concentration of NaC2H3O2 and HC2H3O2 has higher buffer capacity as it resists pH change to a wider range due to addition of acid or base to the system as compared to low concentration of Buffer A

5 0

3 years ago