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Natalka [10]
3 years ago
9

(Help would be greatly appreciated, chemistry is not my strong suit) How many moles of NaCl are present in a solution with a mol

arity of 8.59M and 125mL of a solution?
1. 1.07g
2. 62.7mol
3. 1.07mol
4. 62.7g
Chemistry
1 answer:
tatyana61 [14]3 years ago
8 0

Molarity is a unit of concentration defined as the number of moles of solute (the substance being dissolved) per volume of solution (the solvent in which all the solute is dissolved). Mathematically, molarity is expressed as

M = \frac{\text{ mol solute}}{\text{ L solution}}.

In this question, we are given the molarity and the volume of a solution of NaCl. We can use this information to calculate the number of moles of NaCl present in the solution. Rearranging the equation to solve for moles of solute, we multiply the molarity by the volume of the solution (the units for volume must be in liters, so 125 mL is expressed as the equivalent 0.125 L):

(8.59 \text{ M})(0.125 \text{ L}) = 1.07 \text{ moles of NaCl}.

The question asks for the number of moles of NaCl in this solution, so number 3 would be correct.

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Calculate δ h for the reaction:no (g) + o2 (g) ↔ no2 (g). given: 2o3(g) ↔ 3o2(g) δh=-426 kj o2(g) ↔ 2o(g) δh=+ 490 kj no(g) + o3
maks197457 [2]
To calculate the <span>δ h, we must balance first the reaction: 

NO + 0.5O2 -----> NO2

Then we write all the reactions,

2O3 -----> 3O2    </span><span>δ h = -426 kj        eq. (1)

O2 -----> 2O    </span><span>δ h = 490 kj             eq. (2)

NO + O3 -----> NO2 + O2    </span><span>δ h = -200 kj          eq. (3)


We divide eq. (1) by 2, we get

</span>O3 -----> 1.5O2    δ h = -213  kj             eq. (4)

Then, we subtract eq. (3) by eq. (4) 

NO + O3 ----->  NO2 + O2   δ h = -200 kj
-       (O3 -----> 1.5 O2         δ h = -213  kj)
NO -----> NO2 - 0.5O2        δ h = 13  kj               eq. (5)


eq. (2) divided by -2. (Note: Dividing or multiplying by negative number reverses the reaction)

O -----> 0.5O2  <span>δ h = -245  kj         eq. (6)
</span>
Add eq. (6) to eq. (5), we get

NO -----> NO2 - 0.5O2        δ h = 13  kj 
+  O -----> 0.5O2                 δ h = -245  kj
NO + O ----> NO2               δ h = -232 kj

<em>ANSWER:</em> <em>NO + O ----> NO2               δ h = -232 kj</em>


4 0
3 years ago
the red line observed in the line spectrum for hydrogen has 3.03x10^-19J, what is the wavelength, in nm, of this?
djverab [1.8K]

Answer:

λ = 6.5604 x 1016 nm

Explanation:

Given Data:

The energy of the red line in Hydrogen Spectra = 3.03 x 10-19

Formula to calculate Wave length

E= hv

Where E is Energy

h is Planks Constant = 6.626 x 10–34 J s

v is frequency

In turn

v= c/ λ

where c is speed of light = 3.00 x 108 m s–1

λ is wavelength = to find

Solution:

Formula to be Used:

E= hv………………………… (1)

Putting the value v in equation 1

               E= h c/ λ…………………… (2)

Put the value in equation 2

3.03 x 10-19 J  = (6.626 x 10–34 J s) x (3.00 x 108 m s–1) / λ ……………………….(3)

By rearranging equation 3

λ = (6.626 x 10–34 J s) x (3.00 x 108 m s–1) /3.03 x 10-19  J

λ = 6.5604 x 107 m

The answer is in “m”

So we have to convert it into nm

So for this to convert “m” to “nm” multiply the answer with 109

λ = 6.5604 x 107 x 109

λ = 6.5604 x 1016 nm

6 0
4 years ago
knowing that the reaction of potassium in water is extremely exothermic, what would be the problem with adding a large piece of
anygoal [31]

Answer:

Explanation:

If the reaction is really exothermic (and it is) then the water would spatter all over the place. It would boil off if the container could hold it. It would also react according to the following reaction.

You are talking about a reaction like

2K + 2HOH = 2KOH + H2

8 0
3 years ago
In compliance with conservation of energy, Einstein explained that in the photoelectric effect, the energy of a photon (hv) abso
3241004551 [841]

Answer:

 a) 1.866 × 10 ⁻¹⁹ J      b)   3.685 × 10⁻¹⁹ J

Explanation:

the constants involved are

h ( Planck constant) = 6.626 × 10⁻³⁴ m² kg/s

Me of electron = 9.109 × 10 ⁻³¹ kg

speed of light = 3.0 × 10 ⁸ m/s

a) the Ek ( kinetic energy of the dislodged electron) = 0.5 mu²

Ek = 0.5 × 9.109 × 10⁻³¹ × ( 6.40 × 10⁵ )² = 1.866 × 10 ⁻¹⁹ J

b) Φ ( minimum energy needed to dislodge the electron ) can be calculated by this formula

hv =   Φ + Ek

where Ek = 1.866 × 10 ⁻¹⁹ J

v ( threshold frequency ) = c / λ where c is the speed of light and λ is the wavelength of light = 358.1 nm = 3.581 × 10⁻⁷ m

v = ( 3.0 × 10 ⁸ m/s ) / (3.581 × 10⁻⁷ m ) = 8.378 × 10¹⁴ s⁻¹

hv = 6.626 × 10⁻³⁴ m² kg/s ×  8.378 × 10¹⁴ s⁻¹ = 5.551 × 10⁻¹⁹ J

5.551 × 10⁻¹⁹ J = 1.866 × 10 ⁻¹⁹ J + Φ

Φ = 5.551 × 10⁻¹⁹ J - 1.866 × 10 ⁻¹⁹ J = 3.685 × 10⁻¹⁹ J

7 0
3 years ago
Which trait enables a polar bear to survive an extremely cold climate.
blondinia [14]
Thick fur helps a polar bear survive
8 0
3 years ago
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