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3 years ago

What is the molality of an aqueous kbr solution with a mole fraction of kbr, x, equal to 0.245?

1 answer:

4 0

Molality is used to express concentration and it is:
molality = moles of solvent / kilogram solution

Now, lets assume there is one mole of solution. Then, there will be 0.245 moles of KBr and 0.755 moles of water. We multiply these molar fractions with the substances' molar masses to find the weight of one mole of solution.

Weight of one mole of solution = 0.245 * 119 + 0.755 * 18
Weight = 42.74 grams

Converting this weight to kilograms, this is 0.043 kg. We now multiply the moles of KBr by the kilograms of solution to find the molality:

molality = 0.245 / 0.043

The molality of the solution is 5.70 moles per kg

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Chapter 15 of your textbook discusses conjugation and various reactions of 1,3-dienes. In CHE 321, we discussed various ways to

xxMikexx [17]

Answer:

Dienes are alkenes that contain two carbon-carbon double bonds, so they have the same properties as these hydrocarbons.

In the attached file are the two reactions of dienes production.

Explanation:

Two ways to obtain dienes are as follows:

-Reaction of oxidative dehydrogenation of an alkane, is an exothermic process and occurs at lower temperatures, diene and water are formed, generating greater conversion at lower temperature levels.

-Dehydration of primary alcohols. The treatment of alcohols with acid at elevated temperatures produces dienes due to water loss. For example, heating ethanol in the presence of sulfuric acid produces ethene by the loss of a water molecule.

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5 0

3 years ago

1. Pewien tlenek azotu o masie cząsteczkowej 108 u zawiera 74,07% tlenu. Wykonaj stosowne obliczenia i napisz wzór sumaryczny te

love history [14]

Answer:

1. Stąd empiryczny wzór substancji to N₂O₅

2. W związku z tym ilość w gramach chlorku sodu NaCl is 114,4 g.

Explanation:

1. Mamy tutaj;

Masa molowa tlenku azotu = 108u

Masa azotu = 14,0067u

Masa tlenu = 15,999 u

74,07% masy tlenku azotu to tlen

Dlatego masa obecnego tlenu = 108 × 74,07 / 100 = 79,9956 u

Masa obecnego azotu = 108 - 79,9956 = 28,0044u

Liczba moli tlenu = 79,9956 / 15,999 = 5,00003 ≈ 5

Liczba moli azotu = 28,0044 / 14,0067 = 1,99935 ≈ 2

Stąd empiryczny wzór substancji to N₂O₅.

2. Kiedy sód reaguje z chlorem, mamy;

2Na (s) + Cl₂ (g) → 2NaCl (s)

Dlatego 2 mole sodu Na reaguje z 1 molem chloru gazowego Cl₂, z wytworzeniem 2 moli chlorku sodu NaCl

W związku z tym 1 mol sodu Na reaguje z 1/2 molem chloru gazowego Cl₂ z wytworzeniem 1 mola chlorku sodu NaCl

Masa Na obecnego w reakcji = 45 g

Masa molowa sodu = 22,989769u

Liczbę moli sodu w 45 g sodu podano w następujący sposób;

$Liczba \, \, moli \, \, Na= \frac{Mass \, of \, Na}{Molowy \, masa \, z \, Na} = \frac{45}{22.989769} = 1.96 \, mole$

Z czego 1,96 moli sodu Na reaguje z 1/2 × 1,96 mola chloru gazowego Cl₂ z wytworzeniem 1,96 mola chlorku sodu NaCl

Masa molowa NaCl = 58,44 g / mol

Dlatego masa NaCl = liczba moli NaCl × masa molowa NaCl

Masa NaCl = 1,96 × 58,44 = 114,39001 g ≈ 114,4 g

W związku z tym ilość w gramach chlorku sodu NaCl = 114,4 g.

4 0

2 years ago

5. How much heat (in calories) is absorbed by a reaction when

Wewaii [24]

Answer:

1.2 × 10⁴ cal

Explanation:

Given data

Mass of water (m): 300 g

Initial temperature: 80 °C

Final temperature: 40°C

We can calculate the heat released by the water ( $Q_w$ ) when it cools using the following expression.

$Q_w = c \times m \times (T_f - T_i)$

where

c is the specific heat capacity of water (1 cal/g.°C)

$Q_w = \frac{1cal}{g.\°C} \times 300g \times (40\°C - 80\°C) = -1.2 \times 10^{4} cal$

According to the law of conservation of energy, the sum of the heat released by the water ( $Q_w$ ) and the heat absorbed by the reaction ( $Q_r$ ) is zero.

$Q_w + Q_r = 0\\Q_r = -Q_w = 1.2 \times 10^{4} cal$

7 0

2 years ago

Is NaCl CH3OH LiOH or H2SO4 a bronsted acid

vesna_86 [32]

Answer:

D. H₂SO₄

Explanation:

Bronsted acids are those that donate H+ ions. In this question, H₂SO₄ is a Bronsted acid.

Note: H₂SO₄ is one of seven strong acids that you should try to memorize.

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3 years ago

starting with the idea of isostasy and ending with plate tectonics, explain how scientists understanding of the earth's crust ha

anzhelika [568]

Answer:

Isostasy controls the regional elevations of continents and ocean floors in accordance with the densities of their underlying rocks. ... The concept of isostasy played an important role in the development of the theory of plate tectonics.

8 0

2 years ago