Write the name and formula of the compound made of magnesium and fluorine

Besides caffeine what other compound are found in tea leaves?

Vesna [10]

Answer:

Tea also contains two substances related to caffeine: theobromine and theophylline

3 0

2 years ago

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45.6 mL of 0.0600 M Ba(OH)2 is added to 25.0 mL of HCl of unknown concentration. What is the concentration of HCl?

Alex Ar [27]

45.6 mL of 0.0600 M of $Ba(OH)_{2}$ is added to 25.0 mL of HCl of unknown concentration then , the concentration of HCl is 0.032 M .

Calculation ,

Formula used : $M_{1} V_{1}$ = $M_{2} V_{2}$ ...( 1 )

Where $M_{1}$ = concentration of $Ba(OH)_{2}$ = 0.0600 M ( given )

$M_{2}$ = concentration of HCl = ? ( to be find )

$V_{1}$ = volume of $Ba(OH)_{2}$ = 25.0 mL ( given )

$V_{2}$ = volume of HCl = 45.6 mL ( given )

Now , put the value of all volume and concentration in equation ( 1 ) we get .

0.0600 M × 25.0 mL = $M_{2}$ × 45.6 mL

$M_{2}$ = 0.0600 M × 25.0 mL / 45.6 mL = 0.032 M

Therefore , concentration of unknown concentration of HCl is 0.032 M .

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7 0

1 year ago

The energy required to ionize a mole of potassium ions is 419 kJ/mol . What is the longest wavelength of light capable of this i

liraira [26]

First divide the ionization energy by Avogadro's number to get the energy per atom of potassium;
419 kj/mol / 6.023 x 10²³
= 4.19 x 10⁵ / 6.023 x 10²³ = 6.96 x 10⁻¹⁹
E = hc/λ
where lambda (λ) is the wavelength, h is Planck's constant, c is the speed of light
E = 6.96 x 10⁻¹⁹ j/atom
h =6.63x10⁻³⁴ Js
c = 3 x 10⁸ m/s
λ = ?
λ = hc/E = (6.63x10⁻³⁴ x 3 x 10⁸ ) / 6.96 x 10⁻¹⁹ = 285.8nm = 286nm
The longest wavelength of light capable of this ionization is 286nm.

3 0

3 years ago

How would you prepare 500 ml of the following solutions : Sodium succinate buffer (0.1 mol/dm3 pH 5.64)

Nana76 [90]

Answer:

8.10g of sodium succinate must be added and 247mL of 0.1M HCl adding enough water until make 500mL

Explanation:

Succinic acid has a pKa₂ of 5.63

To solve this question we must find the amount of sodium succinate and 0.1M HCl that we have to add using H-H equation:

pH = pKa + log [A-] / [HA]

5.64 = 5.63 + log [Na₂Succ.] / [HSucc⁺]

0.01 = log [Na₂Succ.] / [HSucc⁺]

1.0233 = [Na₂Succ.] / [HSucc⁺] (1)

As:

0.1M = [Na₂Succ.] + [HSucc⁺] (2)

Replacing (2) in (1):

1.0233 = 0.1M - [HSucc⁺] / [HSucc⁺]

1.0233[HSucc⁺] = 0.1M - [HSucc⁺]

2.033[HSucc⁺] = 0.1M

[HSucc⁺] = 0.0494M

[Na₂Succ] = 0.0506M

Both [Na₂Succ⁺] and [HSucc⁺] ions comes from the same sodium succinate we have to find the moles of sodium succinate in 500mL of 0.1M. Then, based on the reaction:

Na₂Succ + HCl → HSucc⁺ + Cl⁻

The moles of HCl added = Moles HSucc⁺ we need:

Moles Na₂Succ:

0.500L * (0.1mol/L) = 0.0500 moles

Mass -Molar mass sodium succinate: 162.05g/mol-:

0.0500mol * (162.05g/mol) = 8.10g of sodium succinate must be added

Moles HCl:

0.0494M * 0.500L = 0.0247 moles HCl * (1L / 0.1mol) = 0.247L =

And 247mL of 0.1M HCl adding enough water until make 500mL

7 0

3 years ago

Which is an example of an exothermic process?

Gwar [14]

1) Answer: A hot pack feels warm when chemicals in it combine.

Explanation: Reactions or process in which heat is released(produced) are known as exothermic reactions or process and those in which the heat is absorbed are known as endothermic reactions or process.

If a beaker feels cools when chemical in it react then it means the chemicals have absorbed the heat energy from its surroundings and so it is an example of an endothermic process.

A hot pack feels warm when chemicals in it combine means the energy is released in the chemical reaction and so it is an example of an exothermic process.

Plants use the sun's energy for photosynthesis which is a process of forming food for the plants. Energy acts as a reactant in this process and so it is an example of endothermic process.

Frying an egg by heating it on a stove is an example of an endothermic process as the heat is required to fry the egg.

So, the only exothermic process is the second one, "A hot pack feels warm when chemicals in it combine."

2) In the given equation, heat is written as a product means the heat is released in the equation and so it is an example of an exothermic reaction.

So, the correct choice is the last one " It is exothermic because energy is released."

5 0

3 years ago

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