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Answer:

10.57% of N in acetanilide

Explanation:

All nitrogen in the sample is converted in NH₃ in the Kjeldahl determination. The NH₃ reacts with H₂SO₄ as follows:

2NH₃ + H₂SO₄ → 2NH₄⁺ + SO₄²⁻

The acid in excess in titrated with Na₂CO₃ as follows:

Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂

To solve this question we must find the moles of sodium carbonate = Moles of H₂SO₄ in excess. The added moles - Moles in excess = Moles of sulfuric acid that reacts:

Moles Na₂CO₃ anf Moles H₂SO₄ in excess:

0.025L * (0.05mol / L) = 1.25x10⁻³ moles Na₂CO₃ / 0.01360L =

0.09191M * 0.250L = 0.0230 moles H₂SO₄ in excess.

Moles H₂SO₄ added:

0.050L * (0.50mol / L) = 0.0250 moles H₂SO₄ added

Moles that react:

0.0250 moles - 0.0230 moles = 0.0020 moles H₂SO₄

Moles of NH₃ = Moles N:

0.0020 moles H₂SO₄ * (2mol NH₃ / 1mol H₂SO₄) = 0.0040 moles NH₃ = Moles N

mass N and mass percent:

0.0040 moles N * (14g / mol) = 0.056gN / 0.53g * 100 =

Answer:

12

Explanation:

i feel like its 12 because moles are medium sized but are they adult moles or baby moles or growing moles

Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, 0.803moles of nitrogen gas  are there in  a 18 L tank of nitrogen gas at STP.

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.

Mathematically,

number of moles of any ideal gas =given volume ÷Volume occupied by one mole of a ideal gas at STP

Volume occupied by one mole of a ideal gas at STP=22.4L

given volume of nitrogen gas= 18 L

substituting all the given values in the above equation we get,

number of moles of nitrogen gas =18 L ÷22.4L

number of moles of nitrogen gas =0.803moles

Therefore, 0.803moles of nitrogen gas  are there in  a 18 L tank of nitrogen gas at STP.

To know more about mole, here:

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Answer:

1. an educated guess

2. data

3. what changes in experiment

4. what stays the same in both groups

5. the group where nothing changes, normal

6. group with independent variable, what's being tested

Answer:

When these chemical bonds form, atoms of some elements have a greater ability to attract the valence electrons involved in the bond than other elements. Electronegativity is a measure of the ability of an atom to attract the electrons when the atom is part of a compound. Electronegativity differs from electron affinity because electron affinity

HOPE IT HELPS

Explanation:

Answer:

it is electronegativity and it increases as you move up and to the right on the periodic table and nonmetals are situated to the top right of the periodic table

Explanation:

Answer:

Endocrine glands make chemicals called hormones and pass them straight into the bloodstream. Hormones can be thought of as chemical messages. From the blood stream, the hormones communicate with the body by heading towards their target cell to bring about a particular change or effect to that cell.

Answer:

The correct answer is - An envelope of plasma surrounding the sun.

Explanation:

In the provided diagram the C labeled part of the sun is an envelope of plasma surrounding the sun which is called Solar Corona which makes the outermost layer of the atmosphere of the sun. Solar Corona is hotter in comparison to the surface of the sun itself.

Solar Corona is made up of the fourth state of matter known as plasma that has its magnetic field that determined its structural characteristics. Thus, the correct answer is an envelope of plasma surrounding the sun.

Answer:

person above is correct

Explanation:

I took the quiz and got it right.

Answer:

Explanation: Mg(s) + CuSO4 (aq) -> Cu(s) + MgSO4 (aq)

Answer:

Dilute sulfuric acid reacts with metals higher than hydrogen in the reactivity series to form sulfate salts and hydrogen gas. Note the metal reactions are different with concentrated sulfuric acid. Iron is cleaned free from rust prior to coating with tin to form tinplate and with zinc to form galvanized iron.

Answer:

Simply identify what elements are in a compound

Explanation:

For example in NaCl we have sodium (Na) and Chlorine (Cl)

In order to do this you would need to recognise the symbols for a certain element: O for oxygen; N for nitrogen; H for hydrogen etc.

Answer:

C4H10 + 502 -> CO2 + 5H20

......

.......

Answer:

Option A

Explanation:

As we know  

Percent yield is the ratio of actual yield/theoretical yield

a) Percent yield  - Theoretical yield 52.3 g; actual yield 50.7g = 0.97 = 97%

b) Percent Yield - Theoretical yield 17.1 g; actual yield 15.7g = 92%

c) Percent Yield - Theoretical yield 38.8 g; actual yield 36.2 g = 93%

d) Percent Yield - Theoretical yield 24.6 g; actual yield 22.5 g = 91%

Hence option A is correct

Answer:

98.8g (3 s.f.)

Explanation:

Use the mole = mass/mr equation to find the moles of CaO, then use the molar ratio to find the moles of Fe2O3, which is the same as CaO, (assuming the ratio is 1:1, as you haven't stated it clearly in the question). Then use the equation and input to find Mass, which is 98.8g to 3 s.f.

Answer:

C Evidence of Physical change

Explanation:

Because Solid forms is a physical change and so are all the other ones    

Answer: [tex]Fe^{2+}(aq)+2e^-\rightarrow Fe(s)[/tex]

Explanation:

Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.

 Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.

[tex]Mg(s)+Fe^{2+}(aq)\rightarrow Fe(s)+Mg^{2+}(aq)[/tex]

The oxidation half reaction is:

[tex]Mg(s)\rightarrow Mg^{2+}(aq)+2e^-[/tex]

The reduction half reaction is:

[tex]Fe^{2+}(aq)+2e^-\rightarrow Fe(s)[/tex]

Answer:

A

Explanation:

edge

Answer:

3

Explanation:

Answer:

1.) protons or electrons 2.) ion

Explanation:

Answer:

50 moles

Explanation:

took the quiz

Answer:

K

Explanation:

Ionisation energy is the energy required for electron loss and the higher the occupied energy levels=higher atomic radius=the lower the ionisation energy thus k=2.8.8.1

Na=2.8.1

Li=2.1

Answer:

5.13 L

Explanation:

From the question given above, the following data were obtained:

Initial volume (V₁) = 5.33 L

Initial temperature (T₁) = 21 °C

Final temperature (T₂) = 10 °C

Final volume (V₂) =?

Next, we shall convert celsius temperature to Kelvin temperature. This can be obtained as follow:

T(K) = T(°C) + 273

Initial temperature (T₁) = 21 °C

Initial temperature (T₁) = 21 °C + 273

Initial temperature (T₁) = 294 K

Final temperature (T₂) = 10 °C

Final temperature (T₂) = 10 °C + 273

Final temperature (T₂) = 283 K

Finally, we shall determine the final volume. This can be obtained as follow:

Initial volume (V₁) = 5.33 L

Initial temperature (T₁) = 294 K

Final temperature (T₂) = 283 K

Final volume (V₂) =?

V₁/T₁ = V₂/T₂

5.33 / 294 = V₂ / 283

Cross multiply

294 × V₂ = 5.33 × 283

294 × V₂ = 1508.39

Divide both side by 294

V₂ = 1508.39 / 294

V₂ = 5.13 L

Thus, the new volume of the football is 5.13 L

Answer:

18.32L

Explanation:

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Answer:

127°C

Explanation:

This excersise can be solved, with the Charles Gay Lussac law, where the pressure of the gas is modified according to absolute T°.

We convert our value to K → -73°C + 273 = 200 K

The moles are the same, and the volume is also the same:

P₁ / T₁ = P₂ / T₂

But the pressure is doubled so: P₁ / T₁ = 2P₁ / T₂

P₁ / 200K = 2P₁ / T₂

1 /2OOK = (2P₁ / T₂) / P₁

See how's P₁ term is cancelled.

200K⁻¹ = 2/ T₂

T₂ = 2 / 200K⁻¹  → 400K

We convert the T° to C → 400 K - 273 = 127°C

Answer:

Substances that absorb energy in the form of heat are

b)endothermic.

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Answer:

An aqueous solution is water that contains one or more dissolved substances. The dissolved substances in an aqueous solution may be solids, gases, or other liquids.

Answer:

C.

Explanation:

Slightly negative near the oxygen atom and slightly positive near the hydrogen atoms