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3 years ago

Which phrase best defines a covalent bond?

1 answer:

5 0

The answer is c

This becouse In covalent bonding electrons are shared between atoms rather than donated in order for the atoms of both elements to gain full outer shells. Electrons are always shared in pairs. Example: An example of covalent bonding is the molecule of carbon dioxide

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For each of the acid–base reactions, calculate the mass (in grams) of each acid necessary to completely react with and neutraliz

LiRa [457]

Acid-base neutralization reaction is defined as reaction of acid with base to form corresponding salt and water. Strong acid and base completely neutralize each other.

(a) The acid base neutralization reaction is as follows:

$HCl(aq)+NaOH(aq)\rightarrow H_{2}O(l)+NaCl(g)$

From the above balanced chemical reaction, 1 mol of NaOH completely reacts with 1 mol of HCl. The mass of NaOH is given 4.85 g, convert this into number of moles as follows:

$n=\frac{m}{M}$

Molar mass of NaOH is 39.997 g/mol, thus,

$n=\frac{4.85 g}{39.997 g/mol}=0.121 mol$

Thus, 0.121 mol of NaOH reacts with same amount of HCl and number of moles of HCl will be 0.121 mol.

Since. molar mass of HCl is 36.46 g/mol, thus, mass can be calculated as follows:

$m=n\times M=0.121 mol\times 36.46 g/mol=4.421 g$

Therefore, 4.421 g of HCl completely reacts with 4.85 g of NaCl.

(b) The acid base neutralization reaction is as follows:

$2HNO_{3}(aq)+Ca(OH)_{2}(aq)\rightarrow 2H_{2}O(l)+Ca(NO_{3})_{2}(aq)$

From the above balanced chemical reaction, 1 mol of $Ca(OH)_{2}$ completely reacts with 2 mol of $HNO_{3}$ . The mass of $Ca(OH)_{2}$ is given 4.85 g, convert this into number of moles as follows:

$n=\frac{m}{M}$

Molar mass of $Ca(OH)_{2}$ is 74.093 g/mol, thus,

$n=\frac{4.85 g}{74.093 g/mol}=0.06545 mol$

Thus, 0.06545 mol of $Ca(OH)_{2}$ reacts with $2\times 0.06545 mol=0.13091 mol$ of $HNO_{3}$

Since. molar mass of $HNO_{3}$ is 63.01 g/mol, thus, mass can be calculated as follows:

$m=n\times M=0.13091 mol\times 63.01 g/mol=8.25 g$

Therefore, 8.25 g of $HNO_{3}$ completely reacts with 4.85 g of $Ca(OH)_{2}$ .

$H_{2}SO_{4}(aq)+2 KOH (aq)\rightarrow 2H_{2}O(l)+K_{2}SO_{4}(aq)$

From the above balanced chemical reaction, 2 mol of KOH completely reacts with 1 mol of $H_{2}SO_{4}$ . The mass of KOH is given 4.85 g, convert this into number of moles as follows:

$n=\frac{m}{M}$

Molar mass of KOH is 56.1056 g/mol, thus,

$n=\frac{4.85 g}{56.1056 g/mol}=0.0864 mol$

Thus, 0.0864 mol of KOH reacts with $\frac{0.0864 mol}{2}=0.0432 mol$ of $H_{2}SO_{4}$

Since. molar mass of $H_{2}SO_{4}$ is 98.079 g/mol, thus, mass can be calculated as follows:

$m=n\times M=0.0432 mol\times 98.079 g/mol=4.24 g$

Therefore, 4.24 g of KOH completely reacts with 4.85 g of $H_{2}SO_{4}$ .

8 0

4 years ago

Gas Law- please help!!!

jekas [21]

The pressure of the carbon dioxide will be 0.09079 atm.

<h3>What is partial pressure?</h3>

The pressure exerted by the individual gas is known as partial pressure.

The partial pressure is given as

$\rm P_{Total} = P_1 + P_2 + ...$

In a mixture of carbon dioxide and oxygen, 40.0% of the gas pressure is exerted by oxygen.

If the total pressure is 115 mmHg.

The total pressure in atm will be

P = 115 mmHg

P = 0.15132 atm

We have

$\rm P_T \ \ \ = P_{O_2} + P_{CO_2}\\\\0.15132 \ \ = 0.4 \times 0.15132 +P_{CO_2}\\\\ P_{CO_2} = 0.09079\ atm$

Then the pressure of the carbon dioxide will be 0.09079 atm.

More about the partial pressure link is given below.

brainly.com/question/13199169

#SPJ1

8 0

2 years ago

How many joules of heat are absorbed when 1000g of water is heated from 18Celsius to 85celsius?

o-na [289]

Answer + Explanations

Calculate heat absorption using the formula:

Q = mc∆T

Q means the heat absorbed, m is the mass of the substance absorbing heat, c is the specific heat capacity and ∆T is the change in temperature.

The heat absorbed is calculated by using the specific heat of water and the equation ΔH=cp×m×ΔT. 4. Water is vaporized to steam at 100oC. The heat absorbed is calculated by multiplying the moles of water by the molar heat of vaporization.

You can do this easily: just multiply the heat capacity of the substance you're heating by the mass of the substance and the change in temperature to find the heat absorbed.

To calculate the amount of heat released in a chemical reaction, use the equation Q = mc ΔT, where Q is the heat energy transferred (in joules), m is the mass of the liquid being heated (in kilograms), c is the specific heat capacity of the liquid (joule per kilogram degrees Celsius), and ΔT is the change in ...

Q = mc∆T. Q = heat energy (Joules, J) m = mass of a substance (kg) c = specific heat (units J/kg∙K) ∆ is a symbol meaning "the change in"

Precisely, water has to absorb 4,184 Joules of heat (1 calorie) for the temperature of one kilogram of water to increase 1°C. For comparison sake, it only takes 385 Joules of heat to raise 1 kilogram of copper 1°C.

A reaction that absorbs heat is endothermic. Its enthalpy will be positive, and it will cool down its surroundings. This reaction is exothermic (negative enthalpy, release of heat).

Quantitative experiments show that 4.18 Joules of heat energy are required to raise the temperature of 1g of water by 1°C. Thus, a liter (1000g) of water that increased from 24 to 25°C has absorbed 4.18 J/g°C x 1000g x 1°C or 4180 Joules of energy.

6 0

3 years ago

"how many grams of calcium are consumed when 156.8 ml of oxygen"

Akimi4 [234]

Your question is incomplete. However, I found a similar problem fromanother website as shown in the attached picture.

To solve this problem, you must know that at STP, the volume for any gas is 22.4 L/mol. So,

Moles O₂: 156.8 mL * 1 L/1000 mL* 1 mol/22.4 L = 0.007 moles
Mass calcium: 0.007 mol O₂ * 2 mol Ca/1 mol O₂ * 40 g/mol Ca =<em> 0.56 g Ca</em>

3 0

3 years ago

A 118-ml flask is evacuated and found to have a mass of 97.129 g. when the flask is filled with 768 torr of helium gas at 35 ?c,

Inessa05 [86]

The full question asks to decide whether the gas was a specific gas. That part is missing in your question. You need to decide whether the gas in the flask is pure helium.

To decide it you can find the molar mass of the gas in the flask, using the ideal gas equation pV = nRT, and then compare with the molar mass of the He.

From pV = nRT you can find n, after that using the mass of gass in the flask you use MM = mass/moles.

1) From pV = nRT, n = pV / RT

Data:
V = 118 ml = 0.118 liter
R = 0.082 atm*liter/mol*K
p = 768 torr * 1 atm / 760 torr = 1.0105 atm
T = 35 + 273.15 = 308.15 K

n = 1.015 atm * 0.118 liter / [ 0.082 atm*liter/K*mol * 308.15K] =0.00472 mol

mass of gas = mass of the fask with the gas - mass of the flasl evacuated = 97.171 g - 97.129 g = 0.042

=> MM = mass/n = 0.042 / 0.00472 = 8.90 g/mol

Now from a periodic table or a table you get that the molar mass of He is 4g/mol

So the numbers say that this gas is not pure helium , because its molar mass is more than double of the molar mass of helium gas.

7 0

4 years ago