Calculate the specific heat in J/(g·ºC) of an unknown substance if a 2.50-g sample releases 12.0 cal as its temperature changes from 25.0ºC to 20.0ºC. _________J/(g·°C)

Answer:

c

Explanation:

the reason is because your a homosiejenenddj

Answer:

n S = 60 32 = 1.875 , n_S=\tfrac{60}{32}=1.875, nS=3260=1.875, n O = 40 16 = 2.5.

Explanation:

The concentration of a substance can be expressed using molarity, molality or percent.

The term concentration has to do with the amount of substance present in solution. Now let us solve the problems individually;

a) Number of moles =  0.850 grams/80 g/mol = 0.011 moles

molarity = 0.011 moles/345 * 10^-3 L = 0.032 M

b) Number of moles =  13.5g /58 g/mol = 0.23 moles

molality = 0.23 moles/250 * 10^-3 Kg = 0.92 m

c) Number of  moles = 16.5 g/128 g/mol = 0.13 moles

molality = 0.13 moles/54.3  * 10^-3 Kg =2.39 m

d) Total mass present =  12 g +  18 g + 25 g + 500 g = 555 g

mass percent of calcium sulfate =  12 g/555 g * 100/1 = 2.2 %

mass percent of sodium nitrate =  18 g/ 555 g  * 100/1 = 3.2 %

mass percent of potassium chloride = 25 g / 555 g  * 100/1 = 4.5%

mass percent of water =  500 g / 555 g  * 100/1 =90.1%

e) Total mass present = 125 g + 1500g = 1625 g

Mass percent of NaCl =  125 g/1625 g * 100/1 = 7.7%

f) Total volume of solution = 15 L +  28 L  = 43 L

percent by volume of acetone = 15 L/43 L * 100/1 =  34.9%

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For a 21.2 mL sample of a 0.411 M aqueous hydrofluoric acid solution,  the pH after 17.6 mL of barium hydroxide has been added is mathematically given as

pH=3.332

Generally, the equation for the  mole of HF is mathematically given as

mole of HF=molarity*volume

Therefore

mole of HF=0.361*19.2

mole of HF=6.931mmol

The chemical equation

HF+kOH⇆KF+H2O

Therefore

pH=pKa+log(Kf/HF)

pH=3.15+log(6.931*53.6/53.6*4.558)

pH=3.332

In conclusion, The pH

pH=3.332

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Based on the vapor pressure of the pure substances, the mole fraction of pentane is 0.45 and mole fraction of hexane at equilibrium is 0.60.

Vapor pressure of of a liquid is the pressure that is excreted on the walls of a sealed vessel by the molecules of the liquid that have been converted to gaseous phase.

TO determine the mole fraction of pentane in the solution, we use the vapor pressure of the pure substances.

Let the mole fraction of pentane in the mixture be X.

The mole fraction of hexane will be 1 - X

Vapor pressure of solution = 383 torr

(mole fraction of pentane × vapor pressure of pentane) + (mole fraction of hexane × vapor pressure of hexane) = 383 torr

X × 511 + (1 - X) × 150 = 383

511X - 150X + 150 = 383

511X = 233

X = 0.45

Also , at equilibrium, the vapor pressure of pentane = 0.45 × 511 = 230 torr

mole fraction of hexane in the vapor that is in equilibrium with this solution = 230/383

mole fraction of hexane at equilibrium = 0.60

Therefore, the mole fraction of pentane is 0.45 and mole fraction of hexane at equilibrium is 0.60.

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The ratio of moles of AI(NO3)3 to moles Na2CO3 in the reaction is 2:3

In the reaction 2 moles of AI(NO3)3 reacted with 3 moles Na2CO3 so the ratio of the moles is 2 is to 3 represented as 2:3

hope it helps

Answer:

Explanation:

You have the equation. Now change the 3.4 g H2 to moles. moles = grams/molar mass

3.4 g/2.016 = 1.686 moles.

Now using the coefficients in the balanced equation, convert moles H2O2 to moles H2O.

1.686 moles H2 x (2 moles H2O/2 moles H2O2) = 1.686 x (2/2) = 1.686 x (1/1) = 1.686 moles H2O.

Now you know that 1 mole of water is composed of 6.022 x 10^23 molecules. So

1.686 moles H2O x (6.022 x 10^23 molecules H2O/1 mole H2O) = ?? molecules.

Answer:

A solid has definite volume and shape, a liquid has a definite volume but no definite shape, and a gas has neither a definite volume nor shape. The change from solid to liquid usually does not significantly change the volume of a substance

Explanation:

no explanation

Becquerel  did not discover that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks

The phenomenon of radioactivity was discovered by the French scientist Henri Becquerel in 1896 when he placed photographic paper in a drawer with some radioactive rocks.

We have to note that Becquerel did not discover that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks hence the stetement is false.

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Answer:

a

Explanation:

On drawing the structure, the most Carbon atoms in a row is 5

The remaining two carbon atoms are connected to the 2nd carbon atom

IUPAC name is :

Answer:

.926 moles

Explanation:

Rounding :

H2 0 = 18 gm/mole

   50 gm would then be   50 / 18 = 2.7777 moles of water

every two moles of 2 C6H6   produces   6 moles of water

   2.7777/6  * 2 = .926 moles

Quartz is not regarded as an example of a modified silicate.

This is defined as a hard, crystalline mineral composed of silica with a tetrahedral shape. Silica is also referred to as Silicon dioxide(SiO₂).

This type of mineral is a naturally occurring crystal and isn't a modified silicate but the rest can be modified using their respective constituents thereby making option D the most appropriate choice.

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Answer:

22.25 °C

Explanation:

Determine the final temperature when a 25.0 g piece of iron at 85.0 °C is placed into 75.0 grams of water at 20.0 °C.

Answer:

About 11.0 moles.

Explanation:

We are given a bottle filled with 1.00 L of sulfur hexafluoride (SF₆) and we want to determine the number of moles of the liquid that is present.

First, determine its mass with the given density:

[tex]\displaystyle \begin{aligned}\rho & = \frac{m}{V} \\ \\ m & = \rho V \\ \\ & = \left(\frac{1.60\text{ g}}{\text{mL}}\right)(1.00\text{ L})\left(\frac{1000\text{ mL}}{1\text{ L}}\right) \\ \\ & = 1.60\times 10^3 \text{ g}\end{aligned}[/tex]

The molecular weight of SF₆ is 146.07 g/mol. Hence:

[tex]\displaystyle 1.60\times 10^3\text{ g SF$_6$} \cdot \frac{1\text{ mol SF$_6$}}{146.07\text{ g SF$_6$}} = 11.0\text{ mol SF$_6$}[/tex]

Therefore, about 11.0 moles of sulfur hexafluoride is present.

Taking into account the Brønsted-Lowry acid-base theory, the reaction between hypoiodous acid and water is:

HOI + H₂O ⇄ OI⁻ + H₃O⁺

The Brønsted-Lowry acid-base theory (or the Brønsted-Lowry theory) identifies acids and bases based on whether the species accepts or donates protons or H⁺.

According to this theory, acids are proton donors while bases are proton acceptors. That is, an acid is a species that donates an H⁺ proton while a base is a chemical species that accepts an H⁺ proton from the acid.

So, reactions between acids and bases are H⁺ proton transfer reactions, causing the acid to form its conjugate base and the base to form its conjugated acid by exchanging a proton.

In this case, the reaction between hypoiodous acid and water is:

HOI + H₂O ⇄ OI⁻ + H₃O⁺

where HOI acts as an acid because it donates a potron, while water acts as a base because it accepts the proton donated by HOI.

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False, there are 9 named classes of hazardous materials.

Hazardous materials are substances or chemicals that pose a health hazard, a physical hazard, or harm to the environment.

There are 9 hazardous substances symbols you need to know: flammable, oxidising, explosives, gas under pressure, toxic, serious health hazard, health hazard, corrosive and environmental hazard.

Hence, the statement is false.

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Answer:

270 g of water

Explanation:

Answer:

Polar molecule. A neutral, or uncharged molecule that has an asymmetric internal distribution of charge, leading to partially positive and partially negative regions

Cohesion The attraction of molecules for other molecules of the same kind

Adhesion The attraction of molecules for other molecules of a different kind

Density The mass per unit volume of a substance

Specific heat capacity The amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius

Heat of vaporization The amount of energy needed to change one gram of a liquid substance to a gas at constant temperature

Polar substance. a molecule that is neutral or uncharged but has an asymmetric internal charge distribution that produces both positive and negative regions.

Cohesion molecules' attraction to other molecules of the same sort. Adhesion the pull of certain molecules toward others of a different type

Density a substance's mass per unit volume particular heat capacity The amount of heat required to increase a substance's temperature by one degree Celsius in one gram

Vaporization-related heat energy required to convert one gram of a liquid material into a gas at a fixed temperature.

Therefore, Polar substance. a molecule that is neutral or uncharged but has an asymmetric internal charge distribution that produces both positive and negative regions.

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Answer:

Rows on the periodic table represents a period, which is the number of energy levels or rings. It is the last shell which valence electrons are on.

For example the first row waas Hydrogen and Helium which each have one  energy level.

The esecond row has Carbon and Oxygen which has two energy level.

The third row has Sodium which has three energy levels and so on.

The volume of carbon dioxide produced is : 5.4 L

Given data:

moles of propane = 0.080 moles

The chemical reaction

C₃H₈  + 5O₂  ---- > 3CO₂ + 4H₂O

From the reaction

I mole of C₃H₈ = 3CO₂

0.080 moles of C₃H₈ =  3 * 0.080 = 0.24

Applying the equation below to determine the volume of CO₂

Pv = nRT

    = 0.24 * R * T

v = ( 0.24 * 8.314 * 273 ) / 1 atm

  = 544.7 ml = 5.4 L

Hence we can conclude that The volume of carbon dioxide produced is : 5.4 L

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Answer:

silver

5/20

=0.25.................

Answer:

C

Explanation:

Aluminum density = 0.5

Iron density = 2

Gold density = 1

Silver density = 0.25

The smallest value is 0.25 hence silver has less density.

Answer:

gaseous state.

Explanation:

that's the answer

The mass of the sample to methane that contains 3.62×10²⁹ atoms of hydrogen is 4810631.24 g

6.02×10²³ atoms  = 1 mole of Hydrogen

1 mole of Hydrogen = 2 g

Thus,

6.02×10²³ atoms  = 2 g of Hydrogen

Therefore,

3.62×10²⁹ atoms =  (3.62×10²⁹ × 2) / 6.02×10²³

3.62×10²⁹ atoms = 1202657.81 g of Hydrogen

Thus,

4 g of Hydrogen is present in 16 g of methane.

Therefore,

1202657.81 g of Hydrogen will be present in = (1202657.81 × 16) / 4 = 4810631.24 g of methane

Thus, we can conclude that the mass of the sample of methane is 4810631.24 g

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Taking into account the reaction stoichiometry and the definition of STP, 5.4 L of carbon dioxide is produced.

In first place, the balanced reaction is:

C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

The following rule of three can be applied: if by reaction stoichiometry 1 mole of C₃H₈ form 3 moles of CO₂, 0.080 moles of C₃H₈ form how many moles of CO₂?

[tex]amount of moles of CO_{2} =\frac{0.080 moles of C_{3} H_{8}x3 moles of CO_{2} }{1 mole of C_{3} H_{8} }[/tex]

amount of moles of CO₂= 0.24 moles

The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C are used and are reference values for gases. And in these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.

You can apply the following rule of three: If by definition of STP 1 mole of CO₂ occupies 22.4 L, 0.24 moles of CO₂ how much volume does it occupy?

[tex]volume of CO_{2} =\frac{0.24 molesx22.4 L}{1 mole}[/tex]

volume of CO₂= 5.376 L ≅ 5.4 L

Finally, 5.4 L of carbon dioxide is produced.

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the reaction stoichiometry:

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Based on the charge on the aluminium ion, 0.9 g of aluminium are deposited by 0.1 F of electricity.

Electrolysis is the decomposition of a substance known as an electrolyte when electric current is passed through it.

The mass and hence moles an electrolyte deposited when current is passed through it depends on the charge on the ion.

Aluminium ion has a charge of +3 and requires 3F of electricity to deposit 1 mole or 27 g of aluminium

0.1 F will discharge = 0.1/3 × 27 g of aluminium

mass of aluminium deposited = 0.9 g of aluminium.

Therefore, 0.9 g of aluminium are deposited by 0.1 F of electricity.

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Answer:

Depending on the actual amount of water, it's going to overfill.

Explanation:

If your watershed is already one that has a lot of water and is always filled, it's likely that your wetlands and rivers will start to overfill, causing a form of flooding.

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I hope this helps!

-No one

The pH indicators that would be used to determine the unknown substance are :

The pH indicators that can be used to identify the mysterious white powder in the kitchen must be an acid-base indicator such as Litmus or other form of effective pH indicators like methyl orange and Phenol red.

The pH value of the substance as indicated by the acid-base indicators will help to determine what the mysterious white powder is based on the varying pH of the substances resembling the white powder.

Hence we can conclude that The pH indicators that would be used to determine the unknown substance are :Litmus , Methyl orange, Phenol Red.

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Answer:

A

Does it live on land or sea.

Answer:

C:

I would check that does it have hair or not because hair provides info about the DNA which can help me if that specific animal has evolved from DNA of any other animal..

Hope it helped you.