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stiv31 [10]
3 years ago
11

A collection of pennies was investigated. 10.00% were found to have been minted in San Francisco with an average mass of 2.15 g

and 90.00% we’re minted in in Philly with an average mass of 2.156 g. What was the average mass of pennies in this sample? Give the correct answer with the proper amount of significant figures
Chemistry
1 answer:
german3 years ago
5 0

The average mass of the pennies in the sample is 2.16 g.

We have a set of pennies from which 10.00% have an average mass of 2.15 g and 90.00% have an average mass of 2.156 g. The average mass (am) of the whole set is a weighted average, that considers the mass (m) and the percentage (perc) of each group. We can calculate it using the following expression.

am=\frac{\Sigma m \times perc  }{100 \%} = \frac{2.15g \times 10.00\% + 2.156 g \times 90.00\% }{100\%} = 2.1554 g \approx 2.16 g

The average mass of the pennies in the sample is 2.16 g.

You can learn more about weighted average here: brainly.com/question/18554478

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7 0
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8 0
3 years ago
Would you expect the wavelength of maximum absorbance for [Cu(NH3)4]2+ to be greater than or less than the wavelength of maximum
DENIUS [597]

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Less

Explanation:

Since [Cu(NH3)4]2+ and [Cu(H2O)6]2+ are Octahedral Complexes the transitions between d-levels explain the majority of the absorbances seen in those chemical compounds. The difference in energy between d-levels is known as ΔOh (ligand-field splitting parameter) and it depends on several factors:

  • The nature of the ligand: A spectrochemical series is a list of ligands ordered on ligand strength. With a higher strength the ΔOh will be higher and thus it requires a higher energy light to make the transition.
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A partial spectrochemical series listing of ligands from small Δ to large Δ:

I− < Br− < S2− < Cl− < N3− < F−< NCO− < OH− < C2O42− < H2O < CH3CN < NH3 < NO2− < PPh3 < CN− < CO

Then NH3 makes the ΔOh higher and it requires a higher energy light to make the transition, which means a shorter wavelength.

7 0
3 years ago
What is an example of an electrolyte solution?
Karo-lina-s [1.5K]

Answer:

nacl with water

they are capable of conducting electricity

3 0
3 years ago
How many moles of mercury, Hg, are there in 1.30 x 10^7 atoms of murcury? PLEASE HELP, IT'S URGENT! Thank you! (:
vodka [1.7K]
1 mole Hg ---------------- 6.02x10²³ atoms
??  ------------------------- 1.30 x10⁷ atoms

1.30x10⁷ x 1 / 6.02x10²³ =

= 1.30x10⁷ / 6.02x10²³ => 2.159x10⁻¹⁷ moles

hope this helps!

7 0
3 years ago
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