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3 years ago

Calculate the energy gap between the excited and ground states for the sodium ion.

1 answer:

7 0

<span>Answer: Ground state of Hydrogen = -13.6 eV Energy of photon emission: E = hf = hc/Î» = 6.6256E-34 (3E8)/680E-9 E = 0.0292E-17 J(1 eV/1.6E-19 J) = 1.825 eV E(photon) = 1.825 eV Bandgap energy: Î”E = E â€“ Eo = 1.825 â€“ (-13.6) = 15.425 eV</span>

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nswer the following questions relating to HCl, CH3Cl, and CH3Br.HCl(g), can be prepared by the reaction of concentrated H2SO4(ag

alexdok [17]

Answer:

It is an example of double displacement reaction.

4.8 g of NaCl is needed to react.

Explanation:

Balanced reaction: $H_{2}SO_{4}(aq.)+2NaCl(s)\rightarrow 2HCl(g)+Na_{2}SO_{4}(aq.)$

Here, oxidation states of H, S, O, Na and Cl do not change during reaction. Hence it is not a redox reaction.

In this reaction, cations and anions of the reactants interchange their partners during reaction. Hence, it is an example of double displacement reaction.

As $H_{2}SO_{4}(aq.)$ remain in excess amount therefore NaCl (s) is the limiting reagent. Hence production of HCl entirely depends on amount of NaCl used.

Molar mass of HCl = 36.46 g/mol

So, 3.0 g of HCl = $\frac{3.0}{36.46}$ mol of HCl = 0.082 mol of HCl

According to balanced equation-

2 moles of HCl are produced from 2 moles of NaCl

So, 0.082 moles of HCl are produced from 0.082 moles of NaCl

Molar mass of NaCl = 58.44 g/mol

So, mass of 0.082 moles of NaCl = $(0.082\times 58.44)$ g = 4.8 g

Hence 4.8 g of NaCl is needed to react.

4 0

4 years ago

Given the balanced chemical equation, SiO2(s) + 4 HF(g) → SiF4(g) + 2 H2O(l) ΔH°rxn = −184 kJ Determine the mass (in grams) of H

Ostrovityanka [42]

Answer:

mass HF = 150.05 g

Explanation:

SiO2(s) + 4HF(g) → SiF4(g) + 2H2O(l)

⇒ Q = (ΔH°rxn * mHF) / (mol HF * MwHF )

∴ MwHF = 20.0063 g/mol

∴ mol HF = 4 mol

∴ ΔH°rxn = - 184 KJ

∴ Q = 345 KJ

mass HF ( mHF ):

⇒ mHF = ( Q * mol HF * MwHF ) / ΔH°rxn

⇒ mHF = ( 345 KJ * 4mol HF * 20.0063 g/mol ) / 184 KJ

⇒ mHF = 150.05 g HF

3 0

4 years ago

Which equation or rule can be used to estimate the pseudo-critical properties of mixtures based on the pure-component critical c

sveticcg [70]

Answer:

c. Kay's rule

Explanation:

Kay's rule -

The rule is used to determine the pseudo reduced critical parameters of mixture , with the help of using the critical properties of the components of a given mixture .

The equation for Kay's rule is as follows ,

PV = Z RT

Where Z = The compressibility factor of the mixture .

Hence from the given options , the correct answer is Kay's rule .

5 0

3 years ago

Which substance is one that cannot be separated or broken down into simpler substances by chemical means? (Element, pure)

Y_Kistochka [10]

Answer:

gold wire (Au)

Explanation:

A substance that cannot be separated or broken down into simpler substances by chemical means is an element.

Between the given options only gold wire is an element, Au.

A way of knowing that it is an element is noticing that its formula is a single symbol which corresponds to an element found in the periodic table, unlike a combination of said symbols (like NaCl or H₂O).

5 0

3 years ago

Can some body plz help correct me or correct the true or false answers I did wrong. I’m not sure there right :(

3241004551 [841]

4 3 and 5 are wrong:)

4 is true and 5 is false

4. insulators are really thick materials that keep electrons within their space.

For example, a charger the rubber is the insulators and the electrons are flowing inside of the charger so you don't get shocked.

5. without the force of attraction, there are no atoms:)

for number 3, its a trick question

Hope this helped!

(learned these this year so I didn't forget them:)

8 0

3 years ago