Is this a scientific model? Use complete sentences to explain why or why not. (5 points)

The specific heat values of most _____ tend to be quite low

GrogVix [38]

This answer would be heat capacity

4 0

3 years ago

An ideal gas at a given initial state expands to a fixed final volume. would the work be greater if the expansion occurs at cons

crimeas [40]

Answer:

Constant pressure

Explanation:

At constant pressure,

$w = -p\Delta V = -p(V_{f} - V_{i})$

At constant temperature,

$w = -RT \ln \left(\dfrac{V_{f}}{V_{i}} \right)$

1 mol of an ideal gas at STP has a volume of 22.71 L.

Let's compare the work done as it expands under each condition from an initial volume of 22.71 L.

Isobaric expansion

$w = -100p(V_{2} - 22.71}); \text{(1 bar$\cdot$L = 100 J)}$

A plot of -w vs V₂ gives a straight line (red) with a constant slope of 100 J/L as in the diagram below (Note that w is work done on the system, so -w is the work done by the system). \

Isothermal expansion

$w= -8.314 \times 273.15 \ln \left(\dfrac{V_{f}}{22.71} \right)\\\\= -2271 \left( \ln V_{f} -\ln22.71 \right)\\= -2271 \left(\ln V_{f} - 3.123 \right)\\= 7092 - 2271\ln V_{f}$

A plot of -w vs V₂ is a logarithmic curve. Its slope starts at 100 J/mol but decreases as the volume increases (the blue curve below).

Thus, the work done during an expansion at constant pressure is greater than if the system is at constant temperature.

4 0

4 years ago

How does Rb bond with other elements?

Y_Kistochka [10]

Answer: Rb gains two electrons

Explanation:

3 0

3 years ago

Among the elements listed, which would show the largest increase between the second and third ionization energies and why?

Yuri [45]

Ionization energy increases from left to right in the row and from bottom to top in a column. Also as we get closer to the nucleus it would be harder to take electrons out. B (atomic #5) has 2 layers of electron 2 and 3 atom in each layer. P has 15 so it would be 2,8 and 5 respectively. Ca is 20 so 2,8,8,2 and Zn is 30 and it would be 2,18,8,2.
For energy between second and third ionization we are looking at taking out the 3rd electron. B already has 3 electron in the first layer so its easy to take them all. P has 5 in the last layer so again easy. But when we look at Ca and Zn after the 2nd electron (in the last layer) we should change the layer go one layer inside. So this needs more energy. To pick between Zn and Ca (they are in the same row) I mentioned earlier that in one row as we go to the right ionization energy increases so the answer is Zn.

4 0

3 years ago

Starting with acetylene and bromoethane, show how you would use reagents from the table to synthesize 4-methyl-3-hexanone. (ente

Lady_Fox [76]

I have provided the full reaction scheme for the synthesis of 4-methyl-3-hexanone from the reaction of acetylene and bromoethane. Acetylene is initially reacted with NaNH₂ which is a strong base that deprotonates the C-H of the acetylene which creates a carbon nucleophile which will then attack the electrophilic carbon containing the bromo in bromoethane. This is a simple sn2 substitution. Essentially an ethyl group is added to each side of the triple bond in acetylene.

With the 3-hexyne in hand, the triple bond is reduced using Lindlar's catalyst which will hydrogenate only to the alkene and stop. The 3-hexene is then reacted with a peroxycarboxylic acid which is used to epoxidize the alkene, to give the epoxide.

The epoxide is reacted with the grignard reagent which treats the methyl as a strong nucleophile. The methyl adds to one carbon of the epoxide and opens the ring. The acid is added at the end to protonate the alcohol.

Finally, the alcohol is oxidized with chromic acid which will oxidize a secondary alcohol to the ketone. The final product is 4-methyl-3-hexanone.

7 0

3 years ago