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3 years ago

What is the pressure of 4 moles of helium in a 50 L tank at 308k using PV=nRT

Chemistry

2 answers:

Ilya [14]3 years ago

8 0

Hey there!:

p = ??

n = 4 moles

V = 50 L

T = 308 K

R = 0.082 atm

p*V = n * R * T

p * 50 = 4 * 0.082 * 308

p*50 = 101.024

p = 101.024 / 50

p = 2.020 atm

Hope that helps!

Ksju [112]3 years ago

7 0

Answer:

2.02 atm

Explanation:

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Explain why the replacement of the glutamic acid by valine changes the way that molecules of b-globin interact with each other.

aleksandr82 [10.1K]

For the answer to the question above, Hydrophobic regions and hydrophilic regions in the molecules of the b-globin. The replacement causes these hemoglobin molecules to be stickies which gives the cell its sickle shape.
I hope this helps. Have a nice day!

3 0

3 years ago

Calculate the percent by mass of 4.35g of Na I dissolved in 105g of water

Ludmilka [50]

We are given:

Mass of Na added = 4.35 grams

Mass of water = 105 grams

Mass Percent of Na:

Total mass of the solution = mass of solute + mass of solvent

Total mass of the solution = 4.35 + 105 = 109.35 grams

Mass percent of solute = (mass of solute / mass of solution) * 100

Mass percent of Solute = (4.35 / 109.35) * 100

Mass percent = 3.978 %

4 0

2 years ago

Glycolic acid, which is a monoprotic acid and a constituent in sugar cane, has a pKa of 3.9. A 25.0 mL solution of glycolic acid

Phoenix [80]

Answer:

pH = 8.0

Explanation:

First, we have to calculate the moles of NaOH.

$35.8 \times 10^{-3}L.\frac{0.020mol}{L} =7.2\times 10^{-4}mol$

Let's consider the balanced equation.

C₂H₄O₃ + NaOH ⇒ C₂H₃O₃Na + H₂O

The molar ratio C₂H₄O₃: NaOH: C₂H₃O₃Na is 1: 1: 1. So, when 7.2 × 10⁻⁴ moles of NaOH react completely with 7.2 × 10⁻⁴ moles of C₂H₄O₃ they form 7.2 × 10⁻⁴ moles of C₂H₃O₃Na.

The concentration of C₂H₃O₃Na is:

$\frac{7.2\times 10^{-4}mol}{60.8 \times 10^{-3}L} =0.012M$

C₂H₃O₃Na dissociates according to the following equation:

C₂H₃O₃Na(aq) ⇒ C₂H₃O₃⁻(aq) + Na⁺(aq)

C₂H₃O₃⁻ comes from a weak acid so it undergoes basic hydrolisis.

C₂H₃O₃⁻ + H₂O ⇄ C₂H₄O₃ + OH⁻

If we know that pKa for C₂H₄O₃ is 3.9, we can calculate pKb for C₂H₃O₃⁻ using the following expression:

pKa + pKb = 14

pKb = 14 -3.9 = 10.1

10.1 = -log Kb

Kb = 7.9 × 10⁻¹¹

We can calculate [OH⁻] using the following expression:

[OH⁻] = √(Kb.Cb) where Cb is the initial concentration of the base

[OH⁻] = √(7.9 × 10⁻¹¹ × 0.012M) = 9.7 × 10⁻⁷ M

Now, we can calculate pOH and pH.

pOH = -log [OH⁻] = -log (9.7 × 10⁻⁷) = 6.0

pH + pOH = 14

pH = 14 - pOH = 14 - 6.0 = 8.0

7 0

3 years ago

¿Cuántos electrones conforman un enlace doble?

Aleks04 [339]

Answer:

Cada átomo aporta dos electrones al enlace, es decir, se comparten dos pares de electrones entre dos átomos. Un ejemplo es la molécula de Oxígeno (O2).

Explanation:

6 0

3 years ago

A chemist measures the enthalpy change ?H during the following reaction: Fe (s) + 2HCl (g) ? FeCl2 (s) + H2 (g) =?H?157.kJ Use t

erik [133]

Correct Question:

A chemist measures the enthalpy change ΔH during the following reaction: Fe(s) + 2HCl(g)-->FeCl2(s) + H2 ΔH=-157.0 kJ. Use this information to complete the table below. Round each of your answers to the nearest kJ/mol

Answer:

-314 kJ

+628 kJ

+157 kJ

Explanation:

The enthalpy change of a reaction measures the amount of heat that is lost or gained by it. If ΔH >0 the heat is gained, and the reaction is called endothermic, if ΔH<0, the heat is lost, and the reaction is called exothermic.

If the reaction is inverted, the value of ΔH is inverted too (the opposite endothermic reaction is exothermic), and if the reaction is multiplied by a constant, ΔH will be multiplied by it too.

1) 2Fe(s) + 4HCl --> 2FeCl2(s) + 2H2(g)

This reaction is the product of the given reaction by 2, so

ΔH = 2*(-157) = -314 kJ

2) 4FeCl2(s) + 4H2(g) --> 4Fe(s) + 8HCl(g)

This reaction is the inverted reaction given multiplied by 4, so

ΔH = 4*(157) = +628 kJ

3) FeCl2(s) + H2(g) --> Fe(s) + 2HCl

This reaction is the inverted reaction given, so

ΔH = +157 kJ

4 0

3 years ago