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Mila [183]
3 years ago
15

7. Do you have any reservations about taking this course? Explain. How can I help?

Chemistry
1 answer:
Pavel [41]3 years ago
3 0

Answer:

Reservations means to say, are there any thoughts you have about this course that are negative. And what can your teacher do to help you excel, or succeed in this course. Good luck to you, and remember to take deep breathes when you need a break.

Explanation:

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Copper can be also be made by reacting copper oxide with methane
Vsevolod [243]

Answer:

a

Explanation:

3 0
2 years ago
The thyroid, parathyroid, and thymus are located in the
Studentka2010 [4]

Answer:

The pineal, hypothalamus, and pituitary are located in the BRAIN

The thyroid, parathyroid, and thymus are located in the THROAT

The adrenals, pancreas, testes, and ovaries are located in the NEAR THE KIDNEY

Explanation:

The pineal, hypothalamus, and pituitary are located in the BRAIN

The thyroid, parathyroid, and thymus are located in the THROAT

The adrenals, pancreas, testes, and ovaries are located in the NEAR THE KIDNEY

3 0
3 years ago
what mass of sodium fluoride (FW=42.0 g/mol) must be added to 3.50 x 10^2 mL of water to give a solution with pH = 8.40?
MaRussiya [10]

Answer:

Explanation:

Sodium fluoride, being a salt, dissolves in water completely producing F ⁻ ions. Now  F⁻ is the conjugate base of the weak acid HF, so in water we will have the following equilibrium:

F⁻  +  H₂O ⇆ HF + OH⁻

Given this equilibrium, we need to calculate Kb from the Ka for HF,  the [ OH ⁻] from the given pH, and finally the mass needed to produce that  OH⁻ concentration.  

The equilibrium constant, Kb , can be calculated from Kw = Ka x Kb, where Kw = 10⁻¹⁴ and Ka for HF is  6.6 x 10⁻⁴ from reference tables.

Kb = 10⁻¹⁴ / 6.6 x 10⁻⁴ = 1.5 x 10⁻¹¹

pH + pOH = 14  ⇒ pOH = 14 - 8.40 = 5.60

[ OH⁻ ] = 10^-5.60 = 2.51 x 10⁻⁶

Now we have all the information :

                                   F⁻                    HF                        OH⁻

Equilibrium                 X                  2.51 x 10⁻⁶            2.51 x 10⁻⁶

(2.51 x 10⁻⁶)² / X  =  1.5 x 10⁻¹¹     ⇒  X =  (2.51 x 10⁻⁶)²  / 1.5 x 10⁻¹¹

X = [ F⁻ ] = 0.41 M

For 350 mL ( 0.35 L ) we need to add:

0.41 mol HF/ 1 L  *  0.35 L = 0.144 mol

and finally the mass will be:

0.144 mol NaF *  42.0 g/mol NaF = 6.03 g NaF

7 0
3 years ago
Why do we have to add acid to water but not water to acid
KATRIN_1 [288]
It should be CAT!!!!
5 0
3 years ago
An atom has 20 electrons. Find out
Yanka [14]

Answer:

it's atomic number is 5 and total number is 10

8 0
2 years ago
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