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3 years ago

Why is water an extraordinary substance!

1 answer:

4 0

<span>Water has a low molar mass, yet it is a liquid at room temperature.
B) Water is the main solvent within living organisms.
C) Water has an exceptionally high specific heat capacity.
D) Water has strong hydrogen bonding.
E) All of the above.</span>

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Ethanol (C2H5OH) melts a - 144 oC and boils at 78 °C. The enthalpy of fusion of ethanol is 5.02 kj/mol, and its enthalpy of vapo

hammer [34]

<u>Answer:</u>

<u>For a:</u> The total heat required is 36621.5 J

<u>For b:</u> The total heat required is 58944.5 J

<u>Explanation:</u>

<u>For a:</u>

To calculate the heat required at different temperature, we use the equation:

$q=mc\Delta T$ .........(1)

where,

q = heat absorbed

m = mass of substance

$c$ = specific heat capacity of substance

$\Delta T$ = change in temperature

To calculate the amount of heat required at same temperature, we use the equation:

$q=m\times \Delta H$ ........(2)

where,

q = heat absorbed

m = mass of substance

$\Delta H$ = enthalpy of the reaction

The processes involved in the given problem are:

$1.)C_2H_5OH(l)(35^oC)\rightarrow C_2H_5OH(l)(78^oC)\\2.)C_2H_5OH(l)(78^oC)\rightarrow C_2H_5OH(g)(78^oC)$

<u>For process 1:</u>

We are given:

Change in temperature remains the same.

$m=42.0g\\c_l=2.3J/g.K\\T_2=78^oC\\T_1=35^oC\\\Delta T=[T_2-T_1]=[78-35]^oC=43^oC=43K$

Putting values in equation 1, we get:

$q_1=42.0g\times 2.3J/g.K\times 43K\\\\q_1=4153.8J$

<u>For process 2:</u>

We are given:

Conversion factor: 1 kJ = 1000 J

Molar mass of ethanol = 46 g/mol

$m=42.0g\\\Delta H_{vap}=38.56kJ/mol=\frac{35.56kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=773.04J/g$

Putting values in equation 2, we get:

$q_2=42.0g\times 773.04J/g\\\\q_2=32467.7J$

Total heat required = $[q_1+q_2]$

Total heat required = $[4153.8J+32467.7J]=36621.5J$

Hence, the total heat required is 36621.5 J

<u>For b:</u>

The processes involved in the given problem are:

$1.)C_2H_5OH(s)(-155^oC)\rightarrow C_2H_5OH(s)(-144^oC)\\2.)C_2H_5OH(s)(-144^oC)\rightarrow C_2H_5OH(l)(-144^oC)\\3.)C_2H_5OH(l)(-144^oC)\rightarrow C_2H_5OH(l)(78^oC)\\4.)C_2H_5OH(l)(78^oC)\rightarrow C_2H_5OH(g)(78^oC)$

<u>For process 1:</u>

We are given:

Change in temperature remains the same.

$m=42.0g\\c_s=0.97J/g.K\\T_2=-144^oC\\T_1=-155^oC\\\Delta T=[T_2-T_1]=[-144-(-155)]^oC=11^oC=11K$

Putting values in equation 1, we get:

$q_1=42.0g\times 0.97J/g.K\times 11K\\\\q_1=448.14J$

<u>For process 2:</u>

We are given:

$m=42.0g\\\Delta H_{fusion}=5.02kJ/mol=\frac{5.02kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=109.13J/g$

Putting values in equation 2, we get:

$q_2=42.0g\times 109.13J/g\\\\q_2=4583.5J$

<u>For process 3:</u>

We are given:

Change in temperature remains the same.

$m=42.0g\\c_l=2.3J/g.K\\T_2=78^oC\\T_1=-144^oC\\\Delta T=[T_2-T_1]=[78-(-144)]^oC=222^oC=222K$

Putting values in equation 1, we get:

$q_3=42.0g\times 2.3J/g.K\times 222K\\\\q_3=21445.2J$

<u>For process 4:</u>

We are given:

$m=42.0g\\\Delta H_{vap}=38.56kJ/mol=\frac{38.56kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=773.04J/g$

Putting values in equation 2, we get:

$q_4=42.0g\times 773.04J/g\\\\q_4=32467.7J$

Total heat required = $[q_1+q_2+q_3+q_4]$

Total heat required = $[448.14+4583.5+21445.2+32467.7]J=58944.5J$

Hence, the total heat required is 58944.5 J

8 0

3 years ago

Which substances were ionic?

horsena [70]

<h3>Sodium chloride and Sodium bicarbonate are ionic substances</h3><h3>Further explanation </h3>

Atoms have different stability. Unstable atomic atoms will try to form stable electron configurations like those of noble gases. Where noble gases have the number of outer electrons 2 or 8

The formation of electron configurations such as noble gases can be done by sharing electrons with covalent bonds or hand over electrons with ionic bonds

Generally, ionic bonds occur in metals and nonmetallic elements.

While covalent bonds occur because of the use of shared electrons. In general, this bond occurs between nonmetallic elements, which has the same electron attraction

Characteristics of ionic compounds include: solid / crystalline form, soluble in water, conduct electricity

Let see the answer choices

It is a covalent compound because part of the hydrocarbon, a liquid that forms a bond between elements C, H and O, and does not dissolve in water (floats on water)

Cornstarch

Obtained from corn which contains glucose which is a carbohydrate. It does not dissolve in water. Contains a bond between C, H and O. Includes covalent compounds

Sodium chloride
Sodium bicarbonate

Both are ionic compounds, soluble in water, in solid form

NaCl ⇒ Na⁺ + Cl⁻

NaHCO₃⇒ Na⁺ + HCO₃⁻

<h3>Learn more </h3>

ionic bonding

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Type of atoms typically form covalent bonds

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the ionic compound LiI

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Keywords : ionic, covalent, Oil ,Cornstarch ,Sodium chloride,Sodium bicarbonate

#LearnWithBrainly

6 0

3 years ago

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When part of earths surface is tilted towards the sun what does it cause

Furkat [3]

Summer Solstice is what happens when part of the Earth's surface is tilted towards the sun..

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3 years ago

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What devices will you use to measure the mass and the volume in this experiment? (density)

bekas [8.4K]

Answer:

Methods for determining or delivering precise volumes include volumetric pipets and pycnometers; less precise methods include burets, graduated cylinders, and graduated pipets. In this experiment, you will measure masses and volumes to determine density. Four different metal cylinders are investigated.

Explanation:

8 0

2 years ago

Which of the following compounds are soluble in aqueous solutions? Select ALL that are soluble.

sattari [20]

<h3>Answer:</h3>

K₂S
CaSO₄ (slightly soluble in water)
Pb(ClO₄)₂

<h3>Explanation:</h3>

Mg(OH)₂ and CoCO₃ are insoluble in water.
Solubility rules are used to determine whether a compound will be soluble or not soluble in aqueous form.
K₂S is soluble in aqueous solutions as all salts of Potassium are soluble in water.

Calcium (ii) sulfate is slightly soluble in water.
Hydroxides are insoluble in water except, KOH, NaOH and NH₄OH.and Barium hydroxide. Therefore, Mg(OH)₂ is an insoluble hydroxide.

CoCO₃ is insoluble since carbonates are insoluble except K₂CO₃, Na₂CO₃ and (NH₄)₂CO₃. .

Pb(ClO₄)₂ is soluble because all perchlorates are soluble.

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3 years ago