All categories

3 years ago

Help please. The combustion of pentane, C5H12, occurs via the reaction

1 answer:

4 0

If I were you, I'd try to go with this one : $[(6)(-241.8)+(5)(-393.5)]-[-35.1] =-481.6$ . I think that is a solution you have to find. Just use the sum of standard enthalpies of products and of reactants. Hope you will find it helpful!

You might be interested in

Given the Punnett Square above, with Y=dominant yellow allele and y= recessive green allele, what is the probability of an offsp

Mariulka [41]

Answer:

50 percent

Explanation:

7 0

3 years ago

Hardness in groundwater is due to the presence of metal ions, primarily Mg2 and Ca2 . Hardness is generally reported as ppm CaCO

Maslowich

Answer:

0.0144 M

1440 ppm

Explanation:

Ca(In)²⁺ + EDTA → Ca(EDTA)²⁺ + In

We use the volume of EDTA consumed in the titration to calculate the moles of Ca⁺² ions:

0.012 L * 0.0600 M * $\frac{1molCa^{+2}}{1molEDTA}$ = 7.20x10⁻⁴ mol Ca⁺²

Now we calculate the molarity:

7.20x10⁻⁴ mol Ca⁺² / 0.050 L = 0.0144 M

To calculate in ppm, we use the moles of Ca⁺² and convert to mg of CaCO₃:

7.20x10⁻⁴ mol Ca⁺² = 7.20x10⁻⁴ mol CaCO₃

7.20x10⁻⁴ mol CaCO₃ * 100g/mol * $\frac{1000mg}{1g}$ = 72 mg CaCO₃

Finally, the concentration in ppm is:

72 mg CaCO₃ / 0.050L = 1440 ppm

5 0

3 years ago

The order of the layers from the inside of the Earth outwards is:

Ulleksa [173]

I agree with this person

8 0

3 years ago

How does binomial nomenclature related to plants and animals?

goldenfox [79]

Answer:

Binomial Nomenclature is a two-term naming system that uses two different terms to name the species, plants, animals and living organisms. ... The two terms consist of a generic epithet which is genus (category) of that species, and specific epithet which indicates the species itself.

Explanation:

8 0

3 years ago

The quantum numbers for the last electron placed in three elements are listed below. Which of these is(are) NOT correct? Er (4 3

UNO [17]

Answer:

The three elements Erbium, Thallium and Osmium have incorrect quantum numbers for the last electron placed.

Explanation:

The 4 quantum numbers are (n,l,ml,ms):

n (Principal quantum number): it is the number of the shell (level) where the electron is placed.
l (Angular momentum quantum number or Secondary): it represents the sublevel where the electron is placed. There are 4 subleves: s, p d and f so secondary quantum number can take the number 0 (s), 1 (p), 2 (d) or 3 (f) depending on which sublevel the electron is placed.
ml (Magnetic quantum number): it represents the spatial orientation of the electron in respect of the sublevel the electron is placed. For example: if the electron occupies the s sublevel the magnetic number will be 0, if the electron occupies the p sublevel the magnetic number could be -1,0,1, if the electron occupies the d sublevel the magnetic number could be -2,-1,0,1,2 and if the electron occupies the f sublevel the magnetic number could be -3,-2,-1,0,1,2,3. You can see this in the attachment related to the correct sublevel for the example.

ms (Spin quantum number): this number represents the possible rotation of the electron so it could be 1/2 (which is represented by an up arrow) or -1/2 (represented by an down arrow).

Let's analyze the last electron of each element. You can see the attachment for better understanding. The last electron it is represented with orange color.

- Erbium:

This element has 68 electrons so following the Moeller's Diagram to fill the the electronic configuration, we found that the last electron of Erbium it is in the 4th level (shell), in the f sublevel. As Erbium has 12 electrons in the f sublevel, it is necessary to follow the Hund's rule (electrons must be placed singly in every sublevel before place a parallel electron) to placed correctly all of them. Finally, the last electron of Erbium stays in the middle of the sublevel and it is represented by a down arrow so the correct quantum numbers in the Erbium element are (4,3,1,-1/2).

- Thallium:

This element has 81 electrons and following the Moeller's Diagram, we found that it last electron it is in the 6th level, in the p sublevel. As Thallium has 1 electron in the p sublevel, it is placed singly in the sublevel. So the last electron of Thallium it is represented by an up arrow so the correct quantum numbers in the Thallium element are (6,1,-1,1/2).

- Osmium:

Osmium has 76 electrons and following the steps that we did with we the other elements, we noticed that its last electron it is in the 5th level, in the d sublevel. Following the Hund's rule the last electron of Osmium has a magnetic quantum number of -2 and its spin quantum number is -1/2, so the quantum numbers in the Osmium element are (5,2,-2,-1/2).

Note:

- Remember that the s sublevel has place for 2 electrons, the p sublevel has place for 6 electrons, the d sublevel has place for 10 electrons and the f sublevel has place for 14 electrons.

3 0

3 years ago