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11111nata11111 [884]
4 years ago
8

what would you observe if you used a ballpoint pen instead of a pencil to mark the chromatography paper?

Chemistry
1 answer:
sveticcg [70]4 years ago
3 0

Answer:

It basically messes up the results

Explanation:

Pen ink consists of resins, pigments and other colouring dyes dissolved in appropriate solvents like propylene glycol, propyl alcohol and some other ethers. If the ball point pen is used to mark on the chromatography paper then these pigments will also move along with the solvent and interfere with the spots of our analyte.

If you use a ball point pen when doing a chromatogram, then the ink would separate as it is a mixture and run down the paper.

Graphite, or pencil lead however, is not an organic material and therefore will not be affected by common organic solvents used for thin-layer chromatography. Pen ink on the other hand will be readily absorbed by the solvent and will move up the plate.

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solniwko [45]
Some vocabulary word characteristics are active,loyal,humble,gullible and resourceful
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4 years ago
When you standardized the Na2S2O3, what molarity of Na2S2O3 did you obtain?
nikdorinn [45]

Answer:

0.46M NaS₂O₃ (Assuming KIO₃ solution with a concentration of 1.0M)

Explanation:

Based on the reaction:

6 Na₂S₂O₃ + KIO₃ + 5 KI + 3 H₂SO₄ → 3 Na₂S₄O₆ + 3 H₂O + 3 K₂SO₄ + 6 NaI

<em>6 moles of  Na₂S₂O₃ react per mole of KIO₃</em>

Assuming the molarity of the KIO₃ solution is 0,1M:

Moles of KIO₃: = 5.0x10⁻³L ₓ (0.1 mol / L) = <em>5.0x10⁻⁴ moles</em>

As 6 moles of thiosulfate reacted per mole of iodate:

5.0x10⁻⁴ moles KIO₃ ₓ (6 moles Na₂S₂O₃ /  1 mole KIO₃) =

<em>3.0x10⁻³ moles of Na₂S₂O₃. </em>In 6.5mL (6.5x10⁻³L):

3.0x10⁻³moles Na₂S₂O₃ / 6.5x10⁻³ L = 0.46M NaS₂O₃

6 0
3 years ago
Lime is a term that includes calcium oxide (cao, also called quicklime) and calcium hydroxide (ca(oh)2 also called slaked lime).
antiseptic1488 [7]

Answer: - 986.6 kj/mol


Explanation:


1) Equation given:


CaO(s) + H₂O (l) → Ca (OH)₂ (s) δh⁰ = −65.2 kj/mol


2) Standard enthalpies of formation given:


CaO, δhf⁰ = −635.6 kj/mol


H₂O, δhf⁰ = −285.8 kj/mol


3) Calculate the standard enthalpy of formation of Ca(OH)₂.


δh⁰ = ∑δh⁰f of products - ∑ δh⁰f of reactants


Using the mole coefficients of the balanced chemical equation:


δh⁰ = δh⁰f Ca(OH)₂ - δh⁰f CaO - δh⁰f H₂O


⇒ δh⁰f Ca(OH)₂ = δh⁰ + δh⁰f CaO + δh⁰f H₂O


⇒ δh⁰f Ca(OH)₂ = - 65.2 kj/mol − 635.6 kj/mol) − 285.8 kj/mol) = - 986.6 kj/mol.

4 0
3 years ago
Read 2 more answers
Question:<br> What is the molar concentration of 1.29 mol of KCL dissolved in 350 mL of solution?
STatiana [176]

Answer:

M = 3.69 M.

Explanation:

Hello there!

In this case, according to the given information, it turns out possible for us to calculate the molar concentration of the 1.29 moles of KCl in 350 mL of solution by recalling the mathematical definition of molarity as the division of the moles by the volume in liters, in this case 0.350 L; thus, we proceed as follows:

M=\frac{1.29mol}{0.350L}\\\\M=3.69M

Which gives molar units, M, or just mol/L.

Regards!

8 0
3 years ago
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antiseptic1488 [7]

Answer:

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Explanation:is this what you meant?

5 0
3 years ago
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