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3 years ago

Though alchemists were often superstitious, they left a rich legacy for modern chemists. What was their main contribution?

1 answer:

5 0

though alchemists were often superstitious, they left a rich legacy of modern chemists. what was their main contribution-

Explanation:

they were the first to preform experiments.

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Q10.An aqueous solution contains 5.00x10-2 mol/L of Ca2+ and 7.00x10-3 mol/L of SO4

romanna [79]

Answer:

The precipitate will form.

Explanation:

Let's write the equilibrium expression for the solubility product of calcium sulfate:

$CaSO_4(s)$ ⇄ $Ca^{2+}(aq)+SO_4^{2-}(aq)$

The solubility product is defined as the product of the free ions raised to the power of their coefficients, in this case:

$K_{sp}=[Ca^{2+}][SO_4^{2-}]=10^{-4.5}$

Our idea is to find the solubility quotient, Q, and compare it to the K value. A precipitate will only form if Q > K. If Q < K, the precipitate won't form. In this case:

$Q_{sp}=[Ca^{2+}][SO_4^{2-}]=5.00\cdot10^{-2} M\cdot7.00\cdot10^{-3} M=3.5\cdot10^{-4}$

Now given the K value of:

$K_{sp}=10^{-4.5}=3.2\cdot10^{-5}$

Notice that:

$Q_{sp}>K_{sp}$

This means the precipitate will form, as we have an excess of free ions and the equilibrium will shift towards the formation of a precipitate to decrease the amount of free ions.

6 0

4 years ago

A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. How much calcium is contained in 40.0 g of c

Temka [501]

Answer:

20.53 g.

Explanation:

Knowing that every 15.0 g of pure calcium fluoride contains 7.70 g of calcium.

Using cross multiplication:

15.0 g of pure calcium fluoride contains → 7.70 g of calcium.

40.0 g of pure calcium fluoride contains → ??? g of calcium.

∴ The mass of Ca in 40.0 g of calcium fluoride = (7.70 g)(40.0 g)/(15.0 g) = 20.53 g.

6 0

3 years ago

What is a pure substance? What is it made up of?

goblinko [34]

Pure substances are substances that are made up of only one kind of particles and has a fixed or constant structure. They are classified as elements

6 0

4 years ago

The following dipeptide is Asp-Tyr. Indicate the charge state for each structure at the given pH by adding the or – charges to t

AnnZ [28]

Here is the answer. I am not sure how to explain it! Sorry!

3 0

3 years ago

1. Zinc reacts with steam according to the equation:

kvasek [131]

Answer:

1) mass ZnO = 55.155 g

2) V SO2(g) = 18.289 L

Explanation:

1) Zn + H2O → ZnO + H2

∴ mass Zn = 41.6 g

∴ mm Zn = 65.38 g/mol

⇒ mol Zn = (41.6 g)(mol/61.38 g) = 0.678 mol Zn

⇒ mol ZnO = (0.678 mol Zn)(mol ZnO/mol Zn) = 0.678 mol ZnO

∴ mm ZnO = 81.38 g/mol

⇒ mass ZnO = (0.678 mol ZnO)(81.38 g/mol) = 55.155 g ZnO

2) S(s) + O2(g) → SO2(g)

∴ mass S(s) = 24 g

∴ T = 25°C ≅ 298 K

∴ P = 1 atm

∴ mm S(s) = 32.065 g/mol

⇒ mol S(s) = (24 g)(mol/32.065 g) = 0.7485 mol S(s)

⇒ mol SO2(g) = (0.7485 mol S(s))(mol SO2(g)/mol S(s)) = 0.7485 mol SO2(g)

ideal gas:

PV = RTn

⇒ V SO2(g) = ((0.082 atm.L/K.mol)(298 K)(0.7485 mol))/(1 atm)

⇒ V SO2(g) = 18.289 L SO2(g)

6 0

4 years ago