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2 years ago

8

A solution is made by dissolving 3.14 g of NaCl in 79.9 mL of water. What is the concentration of sodium chloride in units of we

ight/volume percent? Group of answer choices 3.78% (w/v) NaCl 96.1% (w/v) NaCl 3.93% (w/v) NaCl 0.0393% (w/v) NaCl

1 answer:

Trava [24]2 years ago

6 0

The concentration of sodium chloride in units of weight/volume percent is 3.93g/ml

Given that

3.93 (w/v) NaCl

Weight NaCl = 3.14g

Volume of water = 79.9mL

W/V is usually represented in g/mL, so no need to change anything

3.14g/79.9mL *100 = 3.93 g/mL (%)

One mole of NaCl contains 6.022 x 10 23 NaCl formula units.

• Use the mole quantity to count formulas by weighing them.

• Mass of a mole of particles = mass of 1 particle x 6.022 x 1023

• The mass of an atom in amu is numerically the same

as the mass of one mole of atoms of the element in grams.

• One atom of sulfur has a mass of 32.07 amu;

one mole of S atoms has a mass of 32.07 g.

Mass of 1 H atom: 1.008 amu x 1.661 x10-24 g/amu = 1.674 x10-24 g

Mass of 1 mole of H atoms:

1.674 x10-24g/H atom x 6.022 x1023H atoms = 1.008 g

Learn more about Weight / volume Percentage here

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CaO + H2O -> Ca(OH)2

yawa3891 [41]

The % yield of Ca(OH)₂ : 62.98%

<h3>Further eplanation </h3>

Percent yield is the compare of the amount of product obtained from a reaction with the amount you calculated

General formula:

Percent yield = (Actual yield / theoretical yield )x 100%

An actual yield is the amount of product actually produced by the reaction. A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients

Reaction

CaO + H₂O ⇒ Ca(OH)₂

mass CaO= 4.2 g

mol CaO(MW=56,0774 g/mol) :

$\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{4.2}{56,0774 g/mol}\\\\mol=0.075$

mol Ca(OH)₂ based on mol CaO

mol ratio CaO : Ca(OH)₂,= 1 : 1, so mol Ca(OH)₂ = 0.075

mass Ca(OH)₂(MW=74,093 g/mol) ⇒ theoretical

$\tt mass=mol\times MW\\\\mass=0.075\times 74,093 g/mol\\\\mass=5.557~g$

% yield :

$\tt =\dfrac{actual}{theoretical}\times 100\%\\\\=\dfrac{3.5}{5.557}\times 100\%\\\\=62.98\%$

8 0

3 years ago

Purification of copper can be achieved by electrorefining copper from an impure copper anode onto a pure copper cathode in an el

givi [52]

Answer: The amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

Explanation:

We are given:

Moles of electron = 1 mole

According to mole concept:

1 mole of an atom contains $6.022\times 10^{23}$ number of particles.

We know that:

Charge on 1 electron = $1.6\times 10^{-19}C$

Charge on 1 mole of electrons = $1.6\times 10^{-19}\times 6.022\times 10^{23}=96500C$

$Cu^{2+}+2e^-\rightarrow Cu$

$2\times 96500=193000C$ is passed to deposit = 1 mole of copper

63.5 g of copper is deposited by = 193000 C

$14\times 1000g=14000g$ of copper is deposited by = $\frac{193000}{63.5}\times 14000=42551181 C$

To calculate the time required, we use the equation:

$I=\frac{q}{t}$

where,

I = current passed = 40.0 A

q = total charge = 42551181 C

t = time required = ?

Putting values in above equation, we get:

$40.0=\frac{42551181 C}{t}\\\\t=1063779sec$

Converting this into hours, we use the conversion factor:

1 hr = 3600 seconds

So, $1063779s\times \frac{1hr}{3600s}=295hr$

Hence, the amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

3 0

3 years ago

What is the difference between a material having the chemical property of being flammable vs having the chemical property of bei

makkiz [27]

Answer:

Being flammable means it supports burning,e.g. Oxygen, but being combustible means burning itself too. e.g. Hydrogen.

Explanation:

Hope it helps!!

4 0

3 years ago

58. A cylinder of a gas mixture used for calibration of blood gas analyzers in medical laboratories contains 5.0% CO2, 12.0% O2,

erica [24]

<em><u>Answer and Explanation:</u></em>

$Greetings!$

$Let's~answer~your~question!$

$Partial ~pressure ~of ~gas ~can ~be ~directly~ calculated ~by ~multiplying ~the~ percentage\\ of~ pressure~ of~ gases~ to ~the ~total ~pressure.$

$\boxed{Pgas~ = ~P~total~ * \% ~P ~of ~gas}$

<em><u>For % of N2 gas: </u></em>

<em><u /></em> $100\% - (5\% + 12\%) = 83\% ~N2$ <em><u /></em>

<em><u /></em>

<em><u /></em> $PN_2 ~= ~146~ atm~ *~ 0.83 ~ = 121.18 ~atm$ <em><u /></em>

<em><u /></em> $PO_2 ~= ~146~ atm~ *~ 0.12~ = 17.52 ~atm$ <em><u /></em>

<em><u /></em> $~PCO_2~ = ~146~ atm ~* 0.05 = 7.3 ~atm$ <em><u /></em>

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4 years ago

A scientist finds an organism that cannot move. It has many cells and get food from its environment. In which Kingdom does it

Allisa [31]

An organism that does not move on its own and makes food from its environment is a producer.

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4 years ago