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Snowcat [4.5K]
2 years ago
9

Which of the following has the correct change in enthalpy and reaction description for the following reaction? NH3(g) + HCl(g) N

H4Cl(s) Given: NH3: ∆H= -46.2 kJ HCl: ∆H= -92.3 kJ NH4Cl: ∆H= -314.43 kJ
Chemistry
2 answers:
Molodets [167]2 years ago
4 0
 <span>2HCl -----> H2 + Cl2 dH = +184.6kJ/mol (equation 1 reversed) 
2NH3 ------> 3H2 + N2 dH = +92.20kJ/mol ( equation 2 unchanged) 
N2 + 4H2 + Cl2 ------> 2NH4Cl dH = - 628.8kJ/mol (equation 3 doubled) 
--------------------------------------... 
Adding up: 2HCl + 2NH3 -----> 2NHCl4 dH = -352kJ/mol 
Hence HCl + NH3 --------> NH4Cl dH = -352/2 = - 176kJ/mol.</span>
Usimov [2.4K]2 years ago
4 0
To find the change in enthalpy (ΔH), all you have to do is use the following formula:

ΔH reaction= [ΔH of products] - [ΔH of reactants]

remember that the products are the ones in the right side of the reaction, and reactants are in the left side. 

ΔH reaction= [ΔH NH4Cl] - [ΔH NH3 + ΔH HCl]

ΔH reaction= [-314.43] - [ -46.2 + -92.3]= -175.93 kJ
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A 3.4 g sample of an unknown monoprotic organic acid composed of C,H, and O is burned in air to produce 8.58 grams of carbon dio
Pavlova-9 [17]

Answer:

C_7H_6O_2

Explanation:

Hello there!

In this case, we can divide the problem in three stages: (1) determine the empirical formula with the combustion analysis, (2) compute the molar mass of acid via the moles of the acid in the neutralization and (3) determine the molecular formula.

(1) In this case, since 8.58 g of carbon dioxide are released, we can first compute the moles of carbon in the compound:

n_C=8.58gCO_2*\frac{1molCO_2}{44.01gCO_2}*\frac{1molC}{1molCO_2}=0.195molC

And the moles of hydrogen due to the produced 1.50 grams of water:

n_H=1.50gH_2O*\frac{1molH_2O}{18.02gH_2O}*\frac{2molH}{1molH_2O}  =0.166molH

Next, to compute the mass and moles of oxygen, we need to use the initial 3.4 g of the acid:

m_O=3.4g-0.195molC*\frac{12.01gC}{1molC}-0.166molH*\frac{1.01gH}{1molH} =0.89gO\\\\n_O=0.89gO*\frac{1molO}{16.0gO}=0.0556molO

Thus, the subscripts in the empirical formula are:

C=\frac{0.195}{0.0556}=3.5 \\\\H=\frac{0.166}{0.0556}=3\\\\O=\frac{0.0556}{0.0556}=1\\\\C_7H_6O_2

As they cannot be fractions.

(2) In this case, since the acid is monoprotic, we can compute the moles by multiplying the concentration and volume of KOH:

n_{KOH}=0.279L*0.1mol/L\\\\n_{KOH}=0.0279mol

Which are equal to the moles of the acid:

n_{acid}=0.0279mol

And the molar mass:

MM_{acid}=\frac{3.4g}{0.0279mol} =121.86g/mol

(3) Finally, since the molar mass of the empirical formula is:

7*12.01 + 6*1.01 + 2*16.00 = 122.13 g/mol

Thus, since the ratio of molar masses is 122.86/122.13 = 1, we infer that the empirical formula equals the molecular one:

C_7H_6O_2

Best regards!

8 0
3 years ago
Bill, a lab technician, was asked to measure out sodium hydroxide (NaOH) for an experiment in a research lab. He was given a cho
Aleks04 [339]

Answer:

He is wrong . Most accurate is Buret .

Explanation:

The number of significant figure denotes the level of accuracy of a measurement .

Beaker can measure liquid in mL upto significant figure of 2 . That means it can measure volume in terms of 10 , 20 , 30mL etc . It can not measure 25 mL

accurately . The last figure of 28 mL is read by guess in the question . So it is not an accurate measurement .

Similarly , graduated cylinder can measure liquid upto significant figure of 3 .  That means it can measure volume in terms of 11 , 22 , 33 mL etc . It can not measure 25.5  mL accurately . The last figure of 28.3  mL is read by guess in the question . So it is less  accurate measurement .

Similarly , buret  can measure liquid upto significant figure of 4 .  That means it can measure volume in terms of 11.2 , 22.3 , 33.5 mL etc . It can not measure 25.53  mL accurately . The last figure of 28.32  mL is read by guess in the question . So it is most accurate among all the three instrument because it can measure accurately mL upto one tenth of it .

7 0
3 years ago
The chart below shows examples of solids, liquids, gases, and plasma.
spin [16.1K]
The word that is in an incorrect place in the chart is HAIL.
The state of matter of hail is not plasma; hail is a solid at room temperature. Plasma refers to the state of matter in which an ionized gas have approximately equal number of positively and negatively charged ions. Thus, plasma is an ionized gas. Plasma is considered to be the fourth state of matter.  <span />
4 0
2 years ago
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Artyom0805 [142]

Answer:

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3 0
2 years ago
What is the mass of 1.2 mol IrI3?​
mr_godi [17]

Answer:

690 g IrI₃

Explanation:

To convert from moles to grams, you have to use the molar mass of the compound. The molar mass of IrI₃ is 572.92 g/mol. You use this as the unit converter in this equation:

1.2molIrI3 * \frac{572.92g}{1mol} = 687.504 g IrI3

Round to the lowest number of significant figures which is 2 to get 690 g IrI₃.

5 0
3 years ago
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