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Elodia [21]
3 years ago
9

A salt crystal has a mass 0.14mg,How many NaCl formula units does it contain?

Chemistry
1 answer:
klemol [59]3 years ago
4 0
To determine the number of formula units in a sample of a compound you need to divide the number of grams by the formula mass. The formula mass of NaCl is 23 g/mol + 35.5 g/mol = 58.5 g/mol, and the number of grams of the sample is 0.14 mg * 1 g/ 1000 mg = 0.00014 g. Then the answer is 0.00014 g / 58.5 g = 2.30 * 10^ -6, which rounded to two significant figures is 2.4 * 10^ -6. So<span> the answer is 2.4 * 10^-6 or 0.0000024</span>
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Calculate the no. of each atoms presents in 10 grams of calcium carbonate.
raketka [301]

Molar Mass of Calcium carbonate:-

\\ \sf\longmapsto CaCO_3

\\ \sf\longmapsto 40u+12u+3(16u)

\\ \sf\longmapsto 52u+48u

\\ \sf\longmapsto 100u

\\ \sf\longmapsto 100g/mol

  • Given Mass=10g

\boxed{\sf No\:of\;moles=\dfrac{Given\:Mass}{Molar\:Mass}}

\\ \sf\longmapsto No\:of\;moles=\dfrac{10}{100}

\\ \sf\longmapsto No\:of\:moles=0.1mol

Now

\boxed{\sf No\:of\:molecules=No\;of\:moles\times Avagadro\: No}

\\ \sf\longmapsto 0.1\times 6.023\times 10^{23}

\\ \sf\longmapsto 6.023\times 10^{22}molecules

8 0
3 years ago
What is the value of the equilibrium constant at 25 oC for the reaction between the pair: I2(s) and Br-(aq) Give your answer usi
insens350 [35]

Explanation:

Formula to calculate standard electrode potential is as follows.

          E^{o}_{cell} = E^{0}_{cathode} - E^{0}_{anode}

                             = 0.535 - 1.065

                             = - 0.53 V

Also, it is known that relation between E^{o}_{cell} and K is as follows.

            E^{o}_{cell} = \frac{RT}{nF} \times ln K

                 ln K = \frac{nFE^{0}_{cell}}{RT}      

Substituting the given values into the above formula as follows.

                 ln K = \frac{nFE^{0}_{cell}}{RT}    

                        =  \frac{2 \times 96485 C mol^{-1} \times -0.53 V}{8.314 l atm/mol K \times 298 K} \times \frac{1 J}{1 V C}  

                ln K = -41.28

                    K = e^{-41.28}    

                        = 1 \times 10^{-18}

Thus, we can conclude that the value of the equilibrium constant for the given reaction is 1 \times 10^{-18}.      

5 0
3 years ago
Consider the following reaction
Fynjy0 [20]

Answer:

92.72 kJ

Explanation:

2 N₂ (g) + O₂ (g) —-> 2 N₂O

According to question , one mole of N₂O requires 163.2 kJ of heat

Molecular weight of N₂O = 44 gm

25 g  N₂O = 25 / 44 mole

25 / 44 mole will require 163.2 x 25 / 44 kJ

= 92.72 kJ

6 0
3 years ago
Which of the following describes a covalent bond?
BaLLatris [955]

I think it is C, because a covalent bond is a distribution of 2 atoms to 1 electron, meaning they are sharing and not exchanging, and the electronegravity would be above 1.7

5 0
3 years ago
Read 2 more answers
You weigh out 0.1183 g of a complex salt to analyze for the percentage of cyanide ion in your complex salt. After dissolving the
Stels [109]

Answer:

25.35%

Explanation:

Again let me restate the the equation of the reaction;

H2O (ℓ) + 2 MnO4 - (aq) + 3 CN- (aq) → 2 MnO2 (s) + 3 CNO- (aq) + 2 OH- (aq)

Amount of potassium permanganate  reacted = 10.2/1000 * 0.08035 = 8.1957 * 10^-4 moles

If 2 moles of MnO4 - reacts with 3 moles of CN-

8.1957 * 10^-4 moles of MnO4 - reacts with 8.1957 * 10^-4 * 3/2

= 1.229 * 10^-3 moles of CN-

Mass of CN- reacted = 1.229 * 10^-3 moles of CN- * 26.02 g/mol

= 0.03 g

Hence, percentage of the cyanide = 0.03 g/0.1183 g * 100

= 25.35%

8 0
3 years ago
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