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Eduardwww [97]
3 years ago
8

True or False ? Endothermic reactions are characterized by net absorption of thermal energy from its surroundings which leads to

an increase in temperature of the surroundings ?
Chemistry
1 answer:
Artemon [7]3 years ago
3 0
False

 Signed by Virtuoso
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Hello, everyone!
marusya05 [52]

Answer: 27.09 ppm and 0.003 %.

First, <u>for air pollutants, ppm refers to parts of steam or gas per million parts of contaminated air, which can be expressed as cm³ / m³. </u>Therefore, we must find the volume of CO that represents 35 mg of this gas at a temperature of -30 ° C and a pressure of 0.92 atm.

Note: we consider 35 mg since this is the acceptable hourly average concentration of CO per cubic meter m³ of contaminated air established in the "National Ambient Air Quality Objectives". The volume of these 35 mg of gas will change according to the atmospheric conditions in which they are.

So, according to the <em>law of ideal gases,</em>  

PV = nRT

where P, V, n and T are the pressure, volume, moles and temperature of the gas in question while R is the constant gas (0.082057 atm L / mol K)

The moles of CO will be,

n = 35 mg x \frac{1 g}{1000 mg} x \frac{1 mol}{28.01 g}

→ n = 0.00125 mol

We clear V from the equation and substitute P = 0.92 atm and

T = -30 ° C + 273.15 K = 243.15 K

V =  \frac{0.00125 mol x 0.082057 \frac{atm L}{mol K}  x 243 K}{0.92 atm}

→ V = 0.0271 L

As 1000 cm³ = 1 L then,

V = 0.0271 L x \frac{1000 cm^{3} }{1 L} = 27.09 cm³

<u>Then the acceptable concentration </u><u>c</u><u> of CO in ppm is,</u>

c = 27 cm³ / m³ = 27 ppm

<u>To express this concentration in percent by volume </u>we must consider that 1 000 000 cm³ = 1 m³ to convert 27.09 cm³ in m³ and multiply the result by 100%:

c = 27.09 \frac{cm^{3} }{m^{3} } x \frac{1 m^{3} }{1 000 000 cm^{3} } x 100%

c = 0.003 %

So, <u>the acceptable concentration of CO if the temperature is -30 °C and pressure is 0.92 atm in ppm and as a percent by volume is </u>27.09 ppm and 0.003 %.

5 0
3 years ago
Caculate the number if moles of the following: 800. g of Ca
Maru [420]
Mole   is  equal  to   mass  of  the  element  divided  by   molar  mass  of  the  element.  that   is
mole=mass/molar  mass
From  periodic  table calcium  has  a   molar  mass  of  40   g/mol
moles  is   therefore  =800g/40g/mol=20moles
3 0
3 years ago
Relative dating methods help scientists to _____.
klasskru [66]
<span>identify the order in which rock units formed</span>
8 0
3 years ago
Read 2 more answers
What is the total pressure of three gases, if the partial pressures are: 2.67 mmHg, 45.29 mmHg, and 789.6 mmHg
EastWind [94]

Answer:

The total pressure of three gases is 837.56 mmHg.

Explanation:

The pressure exerted by a particular gas in a mixture is known as its partial pressure. So, Dalton's law states that the total pressure of a gas mixture is equal to the sum of the pressures that each gas would exert if it were alone:

PT = PA + PB

This relationship is due to the assumption that there are no attractive forces between the gases.

In this case, the total pressure can be calculated as:

PT= 2.67 mmHg + 45.69 mmHg + 789.6 mmHg

Solving:

PT= 837.56 mmHg

<em><u>The total pressure of three gases is 837.56 mmHg.</u></em>

7 0
3 years ago
What is the noble gas notation of Titanium in the ground state?
Bad White [126]
What is the noble gas notation of Titanium in the ground state?
Answer: Titanium atoms have 22 electrons and the shell structure is 2.8. 10.2. The ground state electron configuration of ground state gaseous neutral titanium is [Ar]. 3d2.
4 0
2 years ago
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