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3 years ago

How many moles of MgCl2 are there in 338 g of the compound

Chemistry

1 answer:

krok68 [10]3 years ago

3 0

atomic mass of magnesium = 24.305

atomic mass of chlorine = 35.453

molecular mass of MgCl2 = 24.305+2*35.453 = 95.211

Number of moles in 338 g of pure MgCl2

= 338/95.211 = 3.55001 moles

Ans. there are 3.55 moles of MgCl2 in 338 g of the substance.

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The addition of hydrochloric acid to a silver nitrate solution precipitates silver chloride according to the reaction:

Nimfa-mama [501]

Answer:

Enthalpy change for the reaction is -67716 J/mol.

Explanation:

Number of moles of $AgNO_{3}$ in 50.0 mL of 0.100 M of $AgNO_{3}$

= Number of moles of HCl in 50.0 mL of 0.100 M of HCl

= $\frac{0.100}{1000}\times 50.0$ moles

= 0.00500 moles

According to balanced equation, 1 mol of $AgNO_{3}$ reacts with 1 mol of HCl to form 1 mol of AgCl.

So, 0.00500 moles of $AgNO_{3}$ react with 0.00500 moles of HCl to form 0.00500 moles of AgCl

Total volume of solution = (50.0+50.0) mL = 100.0 mL

So, mass of solution = ( $100.0\times 1.00$ ) g = 100 g

Enthalpy change for the reaction = -(heat released during reaction)/(number of moles of AgCl formed)

= $\frac{-m_{solution}\times C_{solution}\times \Delta T_{solution}}{0.00500mol}$

= $\frac{-100g\times 4.18\frac{J}{g.^{0}\textrm{C}}\times [24.21-23.40]^{0}\textrm{C}}{0.00500mol}$

= -67716 J/mol

[m = mass, c = specific heat capacity, $\Delta T$ = change in temperature and negative sign is included as it is an exothermic reaction]

4 0

3 years ago

Gold has a molar mass of 197 g/mol. (a) how many moles of gold are in a 3.98 g sample of pure gold? (b) how many atoms are in th

Natali5045456 [20]

A.)49.4974874 moles or 49.5 moles
B.)2.980808730172671e+25 or 3e+25

6 0

3 years ago

Explain how lithium atom is positive charge

yulyashka [42]

Lithium is an element that has an electronic configuration of 2,1. So when forming bonds, it tries to release one of its electrons in the last shell to reach the octet state. Normally when atoms release electrons they get positive charge since the number of protons which bear positive charge, is higher than number of electrons which bear negative charge. So when reaching its octet state, lithium gains positive charge!

Hope this helps! Tbh am not good at explaining. If u have any doubts, ask me!

4 0

3 years ago

A concentration cell consisting of two hydrogen electrodes (PH2 = 1 atm), where the cathode is a standard hydrogen electrode and

Lunna [17]

The pH of the unknown solution is 3.07.

Explanation:

1.Find the cell potential as a function of pH

From the Nernst Equation:

Ecell=E∘cell−RT /zF × lnQ

where

R denotes the Universal Gas Constant

T denotes the temperature

z denotes the moles of electrons transferred per mole of hydrogen

F denotes the Faraday constant

Q denotes the reaction quotient

Substitute the values,

E∘cell=0 lnQ=2.303logQ

E0cell=−2.30/RT /zF × log Q

Solving the equation,

2. Find the Q value

Q=[H+]2prod pH₂, product/ [H+]2reactpH₂, reactant

Q=[H+]^2×1/1×1=[H+]2

Taking the log

logQ= log[H+]^2=2log[H+]=-2pH

From the formula,

Ecell=−2.303RT /zF× logQ

E cell= 2.303 × 8.314 CK mol (inverse) × 298.15

K × 2pH /2×96 485 C⋅mol

( inverse)

E cell= 0.0592 V × pH

3. Finding the pH value

E cell= 0.0592 V × pH

pH = E cell/ 0.0592 V= 0.182V/ 0.0592V

pH=3.07

The pH of the unknown solution is 3.07.

7 0

3 years ago

stearic acid and linoleic acid stearic acid and linoleic acid stearic acid has the higher melting point, because it has two more

elena55 [62]

Acid palmitic acid has higher melting point, because it has two more methylene groups.

$\text { Myristic acid } \rightarrow \mathrm{CH}_3\left(\mathrm{CH}_2\right)_{12} \mathrm{COOH} \\& \text { Palmitic acid } \rightarrow \mathrm{CH}_3\left(\mathrm{CH}_2\right)_{14} \mathrm{COOH} \\$

Acid palmitic acid has higher melting point, because it has two more methylene groups.

Giving it a greater surface area and therefore more intermolecular van der waals interact than the myristic acid.

stearic arid $\mathrm{CH}_3\left(\mathrm{CH}_2\right)_{16} \mathrm{COOH}$

linoleic acid $\mathrm{C}_{18} \mathrm{H}_{32} \mathrm{O}_2$ (two double bond)

Stearic acid has higher Melting point, because it does not have any Carbon-Carbon double bonds, whereas linoleic acid has two cis double bonds which prevent the molecules from packing closely together.

Oleic Acid and Linoleic acid.

$\mathrm{C}_{18} \mathrm{H}_{34} \mathrm{O}_2$ -one double bond (cis)

Acid palmitic acid has higher melting point, because it has two more methylene groups.

For more such question on methylene group.

brainly.com/question/4279223

#SPJ4

4 0

1 year ago