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Brilliant_brown [7]
3 years ago
15

What is the percent of oxygen by mass in a pure sample of fecr2o4? 1. 52% 2. 13% 3. 37% 4. 7.1% 5. 29%?

Chemistry
1 answer:
Marta_Voda [28]3 years ago
6 0
Let us suppose that we have 1 mol of FeCr2O4. I'm going to use approximate masses because I have no idea what your periodic table will say. Just put in the exact masses from your periodic table.

Fe = 56
Cr*2 = 2*52 = 104
O4 = 4*16 = 64
===========
Total = 56 + 104 + 64 = 224
The % oxygen = (64 / 224) * 100 = 28.5 % but none of your answers match this. Perhaps you are talking about Fe2(Cr2O4)3 The brackets make all the difference in the world.

Without going through all the detail I did before, The molecular mass is
Fe * 2 = 112
Cr * 6 = 312
O * 12 = 192
The total molecular mass = 616

The % Oxygen = (192 / 616) * 100 = 31% roughly. That answer isn't there either. 

Let's wait and see who else answers.

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Answer:

If the volume of a gas increased from 2 to 6 L while the temperature was held constant, <u><em>the  pressure of the gas decreased by a factor of 3.</em></u>

Explanation:

Boyle's law that says "The volume occupied by a given gaseous mass at constant temperature is inversely proportional to pressure." This means that if the pressure increases, the volume decreases, while if the pressure decreases, the volume increases.

Boyle's law is expressed mathematically as:

Pressure * Volume = constant

or

P * V = k

To obtain the proportionality factor k you must make the quotient:

k=\frac{V2}{V1} =\frac{6 L}{2 L}

k= 3

This means that <u><em>if the volume of a gas increased from 2 to 6 L while the temperature was held constant, the  pressure of the gas decreased by a factor of 3.</em></u>

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Which of the following does not influence the effectiveness of a detergent? A-air temperature B-water temperature C-energy appli
Natasha2012 [34]

<em> A-air temperature does not influence the effectiveness of a detergent</em>

\boxed{\boxed{\bold{Further~explanation}}}

In chemical reactions several factors influence among others:

1. Temperature

The temperature of the reaction that is raised will cause the particles to move more actively so that collisions between particles will become more frequent so that the speed of chemical reactions will be greater

2. Pressure

Addition of pressure will increase the concentration because the volume is reduced, a greater concentration will accelerate the reaction

3. Concentration / substance level

The greater the level, the more substances dissolved and involved in the reaction, thereby increasing the speed of the reaction

4. Stirring

The mechanical force applied to the solution that reacts will cause more collisions to accelerate the reaction

5 Catalysts

Addition of a catalyst to accelerate the reaction without reaction with reactant substances

Detergents are used as cleaning removers of dirt on clothes or oily/fatty items

The main structure of detergent is surfactant which has hydrophobic (binding fat) and hydrophilic (which binds water) parts

Surfactants also function to reduce water surface tension so that it is easier to bind dirt

Surfactants can be anionic in which there are derivatives of Benzene, namely: Alkyl Benzene Sulfonate obtained from sulfonation reactions where hydrogen in benzene is substituted by sulfonate groups (HSO₃⁻) reaction with sulfuric acid (H₂SO₄)

If we see the answer choices:

A. Air temperature

Air does not play a role in the reaction or cleaning process of dirt by detergents, so it is not an effective or ineffective factor in detergent cleaning

B. Water temperature

The right water temperature by adjusting the conditions of clothing materials will increase the effectiveness of detergents, for example, hot temperatures suitable for lifting oil/oil stains, warm/cold temperatures for clothes that are not too dirty and made of silk/wool

C. Energy gave

The energy in the cleaning process can be done through mechanical energy so that the collision between the particles of detergent and dirt will occur more so that faster removal of dirt

D. the length and frequency of the treatment

Sufficient time and the frequency of contact between detergents and ingredients, especially for dirty and hard-to-lose materials, will make removal of dirt better

\boxed{\boxed{\bold{Learn~more}}}

the effect of temperature and surface area on the rate of chemical reactions

brainly.com/question/3790472

The factor causes the particles in a chemical reaction to slow down

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the factor can decrease the rate of a chemical reaction

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factors could be used to increase the reaction rate

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Keywords: detergent, reaction rate, temperature, Catalysts, Pressure, Concentration/substance level

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