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goldfiish [28.3K]
3 years ago
11

What is the mass, in grams, of 7.20×1020 molecules of caffeine, c8h10n4o2?

Chemistry
2 answers:
pickupchik [31]3 years ago
3 0
To determine the mass, you need to know the molecular weight of the c8h10n4o2 . The molecular weight of <span>c8h10n4o2 would be: 8*12 + 10*1 + 4*14 + 2*16= 194g/mol.
To convert the number of molecules into moles, you need to divide it with 6.02 * 10^23. The calculation of the mass of </span>c8h10n4o2 would be: 
(7.20×10^20 molecules)  /(6.02 * 10^23 molecule/mol)  * 194g/mol= 232 * 10^-3 grams= 0.232 grams
stellarik [79]3 years ago
3 0

Answer: 0.23 grams

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to its molecular mass and contains avogadro's number 6.023\times 10^{23} of particles.

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given molecules}}{\text{Avogadro's number}}=\frac{7.20\times 10^{20}}{6.023\times 10^{23}}=1.2\times 10^{-3}moles

1 mole of caffeine (C_8H_{10}N_4O_2) weighs = 194 g

1.2\times 10^{-3}  moles of  (C_8H_{10}N_4O_2) weigh = \frac{194}{1}\times 1.2\times 10^{-3}=0.23g

Thus mass of caffeine (C_8H_{10}N_4O_2) is 0.23 grams.

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Describe what does happen to the electrons when metal atoms are bonded together.
tankabanditka [31]

Answer: In metallic bonds, the valence electrons from the s and p orbitals of the interacting metal atoms delocalize. That is to say, instead of orbiting their respective metal atoms, they form a “sea” of electrons that surrounds the positively charged atomic nuclei of the interacting metal ions. Metals are shiny.

Explanation: Hope this helped!

4 0
3 years ago
Which of these statements is NOT TRUE? Scientists propose explanations that can be explained by examining evidence. Scientists p
Eddi Din [679]

Answer:

The correct option is;

Scientist propose explanations that can be explained by examining evidence

Explanation:

A scientists makes an hypotheses based on possible natural processes to explain the origin and/or the nature of the characteristics of a natural observation. The scientist then source more data and information to put their hypotheses to test. Due to the fact that an hypotheses is based on observable  processes and/or mechanisms, the given hypotheses can be further tested by other scientists through the use of their individually sourced data. From the result of the assessment, the hypotheses can be either accepted or rejected to enable the better clarification of the hypotheses when accepted or the development of a new hypotheses when rejected.

4 0
3 years ago
In a certain industrial process involving a heterogeneous catalyst, the volume of the catalyst (in the shape of a sphere) is 10.
olga nikolaevna [1]

Answer:

a. The second run will be faster.

d. The second run has twice the surface area.

Explanation:

The rate of a reaction is proportional to the surface area of a catalyst. Given the volume (V) of a sphere, we can find its surface area (A) using the following expression.

A=\pi ^{1/3} (6V)^{2/3}

The area of the 10.0 cm³-sphere is:

A=\pi ^{1/3} (6.10.0)^{2/3}=22.4cm^{2}

The area of each 1.25 cm³-sphere is:

A=\pi ^{1/3} (6. 1.25)^{2/3}=5.61cm^{2}

The total area of the 8 1.25cm³-spheres is 8 × 5.61 cm² = 44.9 cm²

The ratio of  8 1.25cm³-sphere to 10.0 cm³-sphere is 44.9 cm²/22.4 cm² = 2.00

Since the surface area is doubled, the second run will be faster.

6 0
3 years ago
an aqueous solution contains 1.2mM of total ions. if the solution is NaCl (aq), what is the concentration of chloride ions?
Genrish500 [490]

Explanation:

As the total concentration is given as 1.2 mM. And, it is also given that salt present in the solution is NaCl.

As sodium chloride is an ionic compound so, when it is added to water then it will dissociate into sodium and chlorine ions as follows.

           NaCl \rightarrow Na^{+} + Cl^{-}

So, it means in total there will be formation of 2 ions when one molecules of NaCl dissociates.

Therefore, concentration of chlorine ions will be calculated as follows.

       Concentration of Cl^{-} ions = \frac{1.2mM}{2}

                                                        = 0.6 mM

Thus, we can conclude that the concentration of chloride ions is 0.6 mM.

5 0
3 years ago
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Hi , the answers must be part B
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