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4 years ago

Total solar eclipses are common and happen every month at the beginning of the new lunar cycle.

1 answer:

7 0

False, solar eclipses happen when the moon moves between the Sun and the Earth, blocking the Sun's rays and casting a shadow on Earth. It happens about once every 18 months (on average)

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Concentration required to begin precipitate pbcl2 for pbcl2 ksp=1. 17×10−5

Ne4ueva [31]

The concentration required to begin to precipitate PbCl2 for PbCl2 is 0.0216 M.

<h3>What is molarity?</h3>

Molarity is the measure of the concentration of any solute in per unit volume of the solution.

The reaction is $\rm Pb^2^+(aq) + 2Cl^-(aq) \rightarrow PbCl_2(s).$

The molarity of lead is 0.025 M

The ksp is given 17×10⁻⁵

Now, calculating the concentration

$[Pb^2^+] = 0.025 M.\\Ksp = 1.17 \times 10^-^5\\Ksp = [Pb^2^+] \times [Cl^-]^2\\[Cl^-] = \dfrac{\sqrt{ Ksp}}{[Pb^2^+]} \\\\[Cl^-] = \dfrac{\sqrt{ 0.0000117}}{0.025} \\[Cl^-] = 2.16 \times 10^-^2M.$

Thus, the concentration required to begin to precipitate PbCl2 for PbCl2 is 0.0216 M.

Learn more about molarity

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5 0

2 years ago

Isotonic saline solution, which has the same osmotic pressure as blood, can be prepared by dissolving 0.923 g of nacl in enough

vova2212 [387]

<span>osmotic pressure = CRT to get C, get the number of moles of NaCl then divide it with volume of the solution mole NaCl = 0.923g / 58.442 g/mol mole NaCl = 0.0158 mol C = 0.0158 mol / 0.1L C = 0.158 mol/L So, osmotic pressure = 0.158 mol/L*(0.082058 L-atm/mol-K)*(25+273K) osmotic pressure = 3.86 atm</span>

8 0

4 years ago

Read 2 more answers

At the end of the Paleozoic Era, ____ covered the Earth. This allowed reptiles to flourish and spread across Earth.

Dafna11 [192]

Answer:

1. grasslands

Explanation: hope this helps :)

8 0

3 years ago

What is the chemical symbol of the terminal atom in the lewis structure of OH- ?

NARA [144]

Answer:

kindly refer to the picture attached

Explanation:

Have a great day . keep smiling

7 0

2 years ago

An unknown compound contains only C , H , and O . Combustion of 5.90 g of this compound produced 11.8 g CO2 and 4.83 g H2O . Wha

Mamont248 [21]

Answer:

C₂H₄O

Explanation:

In a compound that contains Cabon, hydrogen and oxygen, the combustion produce CO₂ from the carbon, and H₂O from the hydrogens. Using the mass of the products we can solve the moles of Carbon and hydrogen. The empirical formula is the simplest whole-number of atoms present in a molecule.

<em>Moles CO₂ = Moles C:</em>

11.8g CO₂ * (1mol / 44g) = 0.268 moles CO₂ = 0.268 moles C * (12g/mol) =

3.216g C

<em>Moles H₂O = 1/2 moles H:</em>

4.83g H₂O * (1mol / 18g) = 0.268 moles H₂O * (2 mol H / 1 mol H₂O) =

0.537 mol H * (1g/mol) = 0.537g H

<em>Mass O to find moles O:</em>

5.90g Sample - 3.216g C - 0.537g H = 2.147g O * (1mol / 16g) = 0.134 moles O

<em>Ratio of atoms -Dividing in 0.134 moles-:</em>

C = 0.268mol C / 0.134 mol O = 2

H = 0.537mol H / 0.134 mol O = 4

O = 0.134mol O / 0.134 mol O = 1

Empirical formula is:

7 0

3 years ago