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2 years ago

What does “circulate” mean in this passage?

Chemistry

2 answers:

IRINA_888 [86]2 years ago

7 0

It means: move or cause to move continuously or freely through a closed system or area.

lisov135 [29]2 years ago

3 0

Answer:

Below

Explanation:

Move or cause to move continuously or freely through the blood.

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A concentrated aqueous solution of Pb(NO3)2 is slowly added to 1.0 L of a mixed aqueous solution containing 0.010 M Na2CrO4 and

Oduvanchick [21]

Answer:

This means the amount of PbCrO4 will precipitate first, with a [Pb^2+] concentration of 1.8*10^-12 M

Explanation:

Step 1: Data given

Molarity of Na2CrO4 = 0.010 M

Molarity of NaBr = 2.5 M

Ksp(PbCrO4) = 1.8 * 10^–14

Ksp(PbBr2) = 6.3 * 10^–6

Step 2: The balanced equation

PbCrO4 →Pb^2+ + CrO4^2-

PbBr2 → Pb^2+ + 2Br-

Step 3: Define Ksp

Ksp PbCrO4 = [Pb^2+]*[CrO4^2-]

1.8*10^-14 = [Pb^2+] * 0.010 M

[Pb^2+] = 1.8*10^-14 /0.010

[Pb^2+] = 1.8*10^-12 M

The minimum [Pb^2+] needed to precipitate PbCrO4 is 1.8*10^-12 M

Ksp PbBr2 = [Pb^2+][Br-]²

6.3 * 10^–6 = [Pb^2+] (2.5)²

[Pb^2+] = 1*10^-6 M

The minimum [Pb^2+] needed to precipitate PbBr2 is 1*10^-6 M

This means the amount of PbCrO4 will precipitate first, with a [Pb^2+] concentration of 1.8*10^-12 M

5 0

3 years ago

Calculate the osmotic pressure of a solution containing 24.6g of glycerin in 250ml of solution at 298K

gavmur [86]

The formula to calculate osmotic pressure is
Osmotic Pressure = M R T
M = Molarity
R = Ideal Gas Constant
T = Temperature in Kelvin

So,
24.6/.2254kg=109.139g /kg >>>>> Molarity
109.139 x mols/92 g = 1.186 mols kg^-1
1.186 x 0.08134 x 298 K = 28.755 atm
1.06852 x 0.08134 x 298K= 26.5 atm

The answer is 26.5

6 0

3 years ago

Calculate the energy required to melt 21 g of ice at 0 oC.

vladimir1956 [14]

We are given:

Mass of ice = 21 grams

The ice is already at 0°c, the temperature at which it melts to form water

Molar heat of fusion of Ice = 6.02 kJ/mol

Finding the energy required:

Number of moles of Ice:

Molar mass of water = 18 g/mol

Number of moles = given mass/ molar mass

Number of moles = 21 / 18 = 7/6 moles

Energy required to melt the given amount of ice:

Energy = number of moles * molar heat of fusion

Energy = (7/6) * (6.02)

Energy = 7.02 kJ OR 7020 joules

7 0

3 years ago

A chemist has synthesized two new dyes based on the molecular structure of plant-based dyes. The lowest energy absorption line f

Nimfa-mama [501]

Answer:

1. The dye that absorbs at 530 nm.

Explanation:

The dye will absorb light to promote the transition of an electron from the HOMO to the LUMO orbital.

The higher the gap, the higher the energy of transition. The energy can be calculated by E = hc/λ, in which h and c are constants and λ is the wavelength.

The equation shows that the higher the energy, the higher the gap and the lower the wavelength.

Therefore, the dye with absorption at 530 nm has the higher HOMO-LUMO gap.

8 0

3 years ago

A sample of water at 100°C is converted to steam after absorbing 820 kJ of heat. How grams of H2O are contained in the sample? A

Varvara68 [4.7K]

Since water is already at 100°C all the energy is used to evaporate it.
Now we can calculate how many mols of water are evaporated with 820kJ.
$N= \frac{820}{41} =20 mol$
We calculated that we got 20 mols of water evaporated. Now, all we have to do is find how many grams is a mol of water. Molar mass of water is 20.16 g/mol.
The final answer is:
$m=20*20.16=403.2g$

7 0

3 years ago