What is one source of human stem cells other than embryos

Identify the substance that conducts electricity. question 19 options: 1) nacl dissolved in water 2) solid nacl 3) solid sugar 4

Delicious77 [7]

The substance that conducts electricity is $NaCl$ dissolved in water.

So, option A is correct one.

When the sodium chloride dissolve in water , the sodium atoms and chlorine atoms separates under the presence of water molecules and exist as sodium cation and chloride anion . Now , they are free to move around in the water as positively and negatively charged ions . This separation of charge allows the solution to conduct electricity.

The solid $NaCl$ and solid sugar does not conduct electricity because it is not dissolve in water . Similarly, sugar dissolved in water does not conduct electricity .

to learn more about conduct electricity.

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4 0

2 years ago

Only the first few meters of the troposphere are heated by__________.

lakkis [162]

Answer:

a

Explanation:

5 0

3 years ago

Read 2 more answers

A chemist must prepare 900.0mL of sodium hydroxide solution with a pH of 13.90 at 25°C. She will do this in three steps: Fill a

Ierofanga [76]

Answer:

28.58 g of NaOH

Explanation:

The question is incomplete. The missing part is:

"Calculate the mass of sodium hydroxide that the chemist must weigh out in the second step"

To do this, we need to know how much of the base we have to weight to prepare this solution.

First we know that is a sodium hydroxide aqueous solution so, this will dissociate in the ions:

NaOH -------> Na⁺ + OH⁻

As NaOH is a strong base, it will dissociate completely in solution, so, starting with the pH we need to calculate the concentration of OH⁻.

This can be done with the following expression:

14 = pH + pOH

and pOH = -log[OH⁻]

So all we have to do is solve for pOH and then, [OH⁻]. To get the pOH:

pOH = 14 - 13.9 = 0.10

[OH⁻] = 10⁽⁻⁰°¹⁰⁾

[OH⁻] = 0.794 M

Now that we have the concentration, let's calculate the moles that needs to be in the 900 mL:

n = M * V

n = 0.794 * 0.9

n = 0.7146 moles

Finally, to get the mass that need to be weighted, we need to molecular mass of NaOH which is 39.997 g/mol so the mass:

m = 39.997 * 0.7146

3 0

4 years ago

The chemistry of nitrogen oxides is very versatile. Given the following reactions and their standard enthalpy changes, (1) NO(g)

AVprozaik [17]

Answer:

The heat of reaction for N₂O₃(g) + N₂O₅(s) → 2 N₂O₄(g) is ΔH = -22.2 kJ

Explanation:

Given the following reactions and their standard enthalpy changes:

(1) NO(g) + NO₂(g) → N₂O₃(g) ΔH o rxn = −39.8 kJ

(2) NO(g) + NO₂(g) + O₂(g) → N₂O₅(g) ΔH o rxn = −112.5 kJ

(3) 2 NO₂(g) → N₂O₄(g) ΔH o rxn = −57.2 kJ

(4) 2 NO(g) + O₂(g) → 2 NO₂(g) ΔH o rxn = −114.2 kJ

(5) N₂O₅(s) → N₂O₅(g) ΔH o subl = 54.1 kJ

You need to get the heat of reaction from: N₂O₃(g) + N₂O₅(s) → 2 N₂O₄(g)

Hess's Law states: "The variation of Enthalpy in a chemical reaction will be the same if it occurs in a single stage or in several stages." That is, the sum of the ∆H of each stage of the reaction will give us a value equal to the ∆H of the reaction when verified in a single stage.

This law is the one that will be used in this case. For that, through the intermediate steps, you must reach the final chemical reaction from which you want to obtain the heat of reaction.

Hess's law explains that enthalpy changes are additive. And it should be taken into account:

If the chemical equation is inverted, the symbol of ΔH is also reversed.
If the coefficients are multiplied, multiply ΔH by the same factor.
If the coefficients are divided, divide ΔH by the same divisor.

Taking into account the above, to obtain the chemical equation

N₂O₃(g) + N₂O₅(s) → 2 N₂O₄(g) you must do the following:

Multiply equation (3) by 2

(3) 2*[2 NO₂(g) → N₂O₄(g) ] ΔH o rxn = −57.2 kJ*2

4 NO₂(g) → 2 N₂O₄(g) ΔH o rxn = −114.4 kJ

Reverse equations (1) and (2)

(1) N₂O₃(g) → NO(g) + NO₂(g) ΔH o rxn = 39.8 kJ

(2) N₂O₅(g) → NO(g) + NO₂(g) + O₂(g) ΔH o rxn = 112.5 kJ

Equations (4) and (5) are maintained as stated.

(4) 2 NO(g) + O₂(g) → 2 NO₂(g) ΔH o rxn = −114.2 kJ

(5) N₂O₅(s) → N₂O₅(g) ΔH o subl = 54.1 kJ

The sum of the adjusted equations should give the problem equation, adjusting by canceling the compounds that appear in the reagents and the products according to the quantity of each of them.

Finally the enthalpies add algebraically:

ΔH= -114.4 kJ + 39.8 kJ + 112.5 kJ -114.2 kJ + 54.1 kJ

ΔH= -22.2 kJ

The heat of reaction for N₂O₃(g) + N₂O₅(s) → 2 N₂O₄(g) is ΔH = -22.2 kJ

8 0

3 years ago

Which one of the following statements is not true?

lana66690 [7]

Answer:

When magma reaches the surface, its dissolved gas content increases is true

Explanation:

The volcanic eruptions happen because of magma that is expelled on the earth’s surface. At the earth’s depth, all magma have gas dissolved in liquid. When the pressure has decreased the magma rises towards the earth’s surface creating a separate vapour phase.

As pressure reduces the volume of gas will expands and giving magma its 'explosive character'. Thus, as magma reaches the surface the dissolved gas content decreases and magma comes out of earth’s surface.

3 0

4 years ago