Which professional most likely uses X-ray technology?

When 2 moles of Fe(s) react with Cl2(g) to form FeCl3(s) according to the following equation, 799 kJ of energy are evolved.

GenaCL600 [577]

Answer:

1. Exothermic.

2. -1598 kJ.

Explanation:

Hello!

1. In this case, according to the reaction, we can infer that 799 kJ of energy are evolved (given off, released) it means that the enthalpy of reaction is negative as the reactants have more energy than the products; which means this is an exothermic reaction.

2. Here, as we know that the enthalpy of reaction is -799 kJ/mol, we can compute the q-value as shown below, considering the reacted 2 moles of solid iron:

$q=2mol*-799 kJ/mol\\\\q=-1598kJ$

Which means that 1598 kJ of energy are evolved when 2 moles of solid iron react.

Best regards!

4 0

3 years ago

A student is given a sample of a blue copper sulfate hydrate. He weighs the sample in a dry covered porcelain crucible and got a

Nata [24]

Answer:

There are present 5,5668 moles of water per mole of CuSO₄.

Explanation:

The mass of CuSO₄ anhydrous is:

23,403g - 22,652g = 0,751g.

mass of crucible+lid+CuSO₄ - mass of crucible+lid

As molar mass of CuSO₄ is 159,609g/mol. The moles are:

0,751g × $\frac{1mol}{159,609g}$ = 4,7052x10⁻³ moles CuSO₄

Now, the mass of water present in the initial sample is:

23,875g - 0,751g - 22,652g = 0,472g.

mass of crucible+lid+CuSO₄hydrate - CuSO₄ - mass of crucible+lid

As molar mass of H₂O is 18,02g/mol. The moles are:

0,472g × $\frac{1mol}{18,02g}$ = 2,6193x10⁻² moles H₂O

The ratio of moles H₂O:CuSO₄ is:

2,6193x10⁻² moles H₂O / 4,7052x10⁻³ moles CuSO₄ = 5,5668

That means that you have <em>5,5668 moles of water per mole of CuSO₄.</em>

I hope it helps!

5 0

4 years ago

Refer to the periodic table tool and write the electron configurations of the following elements in both long and short terms

ahrayia [7]

Answer:-

Carbon

[He] 2s2 2p2

1s2 2s2 2p2.

potassium

[Ar] 4s1.

1s2 2s2 2p6 3s2 3p6 4s1

Explanation:-

For writing the short form of the electronic configuration we look for the nearest noble gas with atomic number less than the element in question. We subtract the atomic number of that noble gas from the atomic number of the element in question.

The extra electrons we then assign normally starting with using the row after the noble gas ends. We write the name of that noble gas in [brackets] and then write the electronic configuration.

For carbon with Z = 6 the nearest noble gas is Helium. It has the atomic number 2. Subtracting 6 – 2 we get 4 electrons. Helium lies in 1st row. Starting with 2, we get 2s2 2p2.

So the short term electronic configuration is [He] 2s2 2p2

Similarly, for potassium with Z = 19 the nearest noble gas is Argon. It has the atomic number 18. Subtracting 19-18 we get 1 electron. Argon lies in 3rd row. Starting with 4, we get 4s1.

So the short electronic configuration is [Ar] 4s1.

For long term electronic configuration we must write the electronic configuration of the noble gas as well.

So for Carbon it is 1s2 2s2 2p2.

For potassium it is 1s2 2s2 2p6 3s2 3p6 4s1

5 0

3 years ago

The following is a list of common errors encountered in research laboratories. Categorize each as a determinate or an indetermin

Kay [80]

Answer:

An unknown being weighed is hygroscopic. - operative error

One component of a mixture being analyzed quantitatively by gas chromatography reacts with the column packing. - methodic error

The tip of the pipet used in the analysis is broken. - instrumental error

In measuring the same peak heights of a chromatogram, two technicians each report different heights - operative error

Explanation:

In chemical analysis, operative errors are that largely introduced into the measurement because of variation of personal judgements of analysts. It is also a personal error that emanates solely due to the analyst.

A methodic error arises as a result of adopting defective experimental methods. For example, a column packing that reacts with a component of the mixture is used in the gas chromatography.

Instrument error refers to the error of a measuring instrument, for instance, the use of a pipette with a broken tip.

4 0

3 years ago

I need help on 26, 28, 36-40

gtnhenbr [62]

26. a megagram = 10⁶ grams while a kilogram = 10³ grams, so the megagram is bigger

28. a mililiter = 10⁻³ liters while a microliter = 10⁻⁶ liters, so the mililiter is bigger

36. 1 meter is equal to 100 centimeters, so the decimal moves right 2 places

37. 1 micrometer is equal to 0.001 milimeters, so the decimal moves left 3 places

38. 1 centimeter is equal to 0.00001 kilometers, so the decimal moves left 5 places

39. 1 micrometer is equal to 10⁻¹² megameters, so the decimal moves left 12 places

40. 1 kilometer is equal to 100000 centimeters, so the decimal moves right 5 places

5 0

3 years ago