How many calcium atoms would be in a 100 g sample of calcium

2 H-H + O=O → 2 H-O-H

There are two moles of H-H bonds and one mole of O=O bonds in one mole of reactants. All of them will break in the reaction. That will absorb

Each mole of the reaction will form two moles of water molecules. Each mole of H₂O molecules have two moles O-H bonds. Two moles of the molecule will have four moles of O-H bonds. Forming all those bond will release

Heat of the reaction:

[tex]\Delta H_{\text{rxn}}[/tex] is negative. As a result, the reaction is exothermic.

In a chemical equation, the arrow  

A. can be read as "yields" or "makes."  

B. always points toward the products.  

C. separates the products and reactants.  

D. all of these

all of these options are right.

Answer:  the answer is all of these

Explanation:

The answer is; It is salt because it is formed by the reaction of an acid and a base.

Salt is composed of cations and anions (with a net charge of 0) joined together by ionic bonds attributed to their complementary charges. NaOH is an alkali salt because it forms an alkaline solution when dissolved in water – because it dissociates hydroxide ions.  

Answer:

the answer is B for short

Explanation:

:)

Any salt, even though it reacts with water, will precipitate out completely when the water is completely evaporated.  If you start with 50 grams of salt, you will end up with 50 grams of salt.

Your answer should be metamorphic rock.

I think the answer is B. Metamorphic rock.

Answer:

0.640 Torr; 1.28 Torr  

Step-by-step explanation:

According to Raoult's Law,

(1) p₁ = χ₁p₁°,  

where p₁ is the solvent

χ₁ + χ₂ = 1                        Subtract χ₁ from each side

      χ₂ = 1 – k₁                          Substitute in (1)

(2)    p₁ = (1 – χ₂)p₁°    Remove parentheses

       p₁ = p₁°- χ₂p₁°      Subtract p₁° from each side

p₁ - p₁° = -χ₂p₁°              Multiply each side by -1

     Δp =   χ₂p₁°

Δp is the vapour pressure lowering.

If the solute is an electrolyte, we must insert the van't Hoff i factor.

ΔP = iχ₂P₁°

===============

(1) Calculate χ₂ for each solution

Water:

1000 g = 1000 × 1/18.02

          = 55.49 mol

      χ₂ = 2.10/(2.10 + 55.49)

          = 2.10/57.59

          = 0.036 46

===============

(2) Calculate the vapour pressure lowering

(a) Sucrose

   i = 1

ΔP = 1 × 0.036 46 × 17.54

ΔP = 0.640 Torr

=====

(b) NaCl

   i = 2

ΔP = 2 × 0.640

ΔP = 1.28 torr

Answer:

A. R represents chemical energy; P represents thermal energy.

Step-by-step explanation:

The molecules in the gas contain chemical energy (R).

When the gas burns, the chemical energy is released as heat, or thermal energy (P).

Answer:

A. R represents chemical energy; P represents thermal energy.

Explanation:

The  change  in pressure in a sealed 10.0L vessel  is 5.28 atm

calculation

The pressure is calculated using the ideal gas equation

That is   P=n RT

where;

P (pressure)= ?

v( volume) = 10.0 L

n( number of moles)  which is calculated as below

write the equation  for  decomposition  of   NH₄NO₂

NH₄NO₂  →  N₂  +2H₂O

Find the moles of NH₄NO₂

 moles = molarity x volume in liters

= 2.40 l x 0.900 M =2.16 moles

Use the mole ratio to determine the  moles of N₂

that is from equation above  NH₄NO₂:N₂ is 1:1 therefore the moles of N₂ is also =2.16 moles

R(gas constant) =0.0821 l.atm/mol.K

T(temperature)  = 25° c  into kelvin = 25 +273 =298 K

make p the  subject of the formula  by diving both side  by  V

P = nRT/V

p ={ (2.16 moles x 0.0821 L.atm/mol.K  x 298 K) /10.0 L} = 5.28  atm.

Answer : The pressure of the gas will be, 5.285 atm

Solution : Given,

Volume of [tex]N_2[/tex] gas = 10 L

Temperature of gas = [tex]25^oC=273+25=298K[/tex]   [tex](0^oC=273K)[/tex]

Volume of [tex]NH_4NO_2[/tex] = 2.40 L

Molarity of the ammonium nitrate solution = 0.9 M

First we have to calculate the moles of ammonium nitrate.

[tex]\text{ Moles of }NH_4NO_2=\text{ Molarity of }NH_4NO_2\times \text{ Volume of }NH_4NO_2[/tex]

[tex]\text{ Moles of }NH_4NO_2=(0.9mole/L)\times (2.40L)=2.16moles[/tex]

The balanced chemical reaction is,

[tex]NH_4NO_2\rightarrow N_2+2H_2O[/tex]

From the balanced reaction, we conclude that

1 mole of [tex]NH_4NO_2[/tex] decomposes to give 1 mole of [tex]N_2[/tex] gas

2.16 moles of [tex]NH_4NO_2[/tex] decomposes to give 2.16 moles of [tex]N_2[/tex] gas

Now we have to calculate the pressure of the gas.

using ideal gas equation,

[tex]PV=nRT[/tex]

where,

P = pressure of the gas

V = volume of the gas

T= temperature of the gas

n = number of moles of gas

R = gas constant = 0.0821 Latm/moleK

Now put all the given values in ideal gas equation, we get pressure of the gas.

[tex]P=\frac{nRT}{V}=\frac{(2.16mole)\times (0.0821Latm/moleK)\times (298K)}{10L}=5.285atm[/tex]

Therefore, the pressure of the gas will be, 5.285 atm

The correct answer is B. hypothesis is falsifiable, but theory has been proven to be correct. A falsifiable thing is something that can be proved as false, also the hypothesis is an explanation that is suggested after an observation process. On the other hand, a theory is a more reliable source because it is verified, checked and proved after certain events that have evidence to certify.

In the late 1800's, experiments using cathode ray tubes led to the discovery of the;

Electron(s)

It was founded that many different metals release cathode rays, and that cathode rays were made of electrons, very small negatively charged particles.

100 centigrams over one gram  is a valid conversion factor. The answer is OPTION D.

A valid conversion factor is a ratio of two equivalent quantities expressed in different units, and it allows you to convert between those units. In this case, centigrams (cg) and grams (g) are both units of mass, but the conversion factor should be based on their relationship as defined in the metric system. In the metric system, there are 100 centigrams in one gram.

This means that one gram is equivalent to 100 centigrams. To convert from grams to centigrams, you would multiply the quantity in grams by 100, and to convert from centigrams to grams, you would divide the quantity in centigrams by 100. The correct conversion factor is a fundamental concept in metric system conversions and scientific measurements.

To learn more about centigrams, click here.

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Antacid generally contains sodium bicarbonate in it.

sodium bicarbonate is a base

Now if we add ant acid in water there will be small amount of effervescence in the glass of water.

However if we add the same ant acid in sprite then there will be large amount of uncontrolled effervescence in the glass.

so we can easily distinguish the two types of glass content.

Answer:

b. Extraction with a solution of sodium hydrogen carbonate, separating the layers, followed by drying and evaporating the organic layer.

Step-by-step explanation:

The ether solution contains your product, benzaldehyde, and some starting material, benzoic acid, the purification steps are:

a. is wrong. Extraction with HCl will not remove much of the benzoic acid.

c. is wrong. If you evaporate the organic layer, you will have a mixture of benzaldehyde and benzoic acid.

d. is wrong. If you work with the aqueous layer, you will end up with benzoic acid,

The amount of HCl in a solution can be calculated by multiplying the solution's volume by its molarity. In the context of gastric acid with a molarity of 3.03x10^-2 M, there are approximately 3.3x10^-4 moles of HCl in 10.9 mL of the solution.

The concentration of a solution is typically expressed in moles per liter (M), which denotes the amount of substance (in moles) present in one liter of the solution. When dealing with hydrochloric acid (HCl) in the context of gastric acid, a solution's molarity can be used to calculate the amount of HCl in a specific volume of the solution.

Given that the concentration of HCl in the gastric acid is 3.03x10^-2 M, there are 3.03x10^-2 moles of HCl in one liter of the solution. We are interested in finding out how many moles of HCl are present in 10.9 mL (or 0.0109 L) of the solution. This can be done by multiplying the volume of the solution by its molarity:

Moles of HCl = Volume in L x Molarity

Moles of HCl = 0.0109 L x 3.03x10^-2 M

So, the quantity of HCl in 10.9 mL of gastric acid is approximately 3.3x10^-4 moles.

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The number of moles of HCl in 10.9 mL of stomach acid that is 3.03x10^-2 M can be calculated using the concentration and volume. The result is 3.32x10^-4 moles of HCl.

The stomach acid is primarily composed of HCl and has a pH range of 1 to 4. To determine the number of moles of HCl in 10.9 mL of stomach acid that is 3.03x10^-2 M in HCl, we can use the formula:

Moles of solute (HCl) = concentration (M) x volume (L)

Converting the volume of stomach acid from mL to L (10.9 mL = 0.0109 L) and substituting the given values into the formula:

Moles of HCl = 3.03x10^-2 M x 0.0109 L = 3.32x10^-4 moles

Therefore, there are 3.32x10^-4 moles of HCl in 10.9 mL of the stomach acid.

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Answer:

C) The half life of carbon-14 is about 5700 years and is too short to date rocks.  

Step-by-step explanation:

The practical limit for carbon dating is about nine half-lives (50 000 yr).

At that point, the amount of carbon remaining has dropped to about 0.2 % of the original amount.

The experimental uncertainties involved become so large that carbon dating is no longer reliable.

Most rocks hundreds of millions or even billions of years old.

Any radioactive carbon would have long since decayed to unmeasurable levels.

A) is wrong. Many rocks contain carbon, but they are so old that the amount of radioactive carbon has dropped below measurables.

B) is wrong. The half-life of carbon is too short to use for dating rocks.

D) is wrong. About 20 % of the carbon in rocks comes from living things that were embedded in layers of mud.

===============

Uranium-238 and lead-206 have half-lives of 4.5 × 10⁹ yr, which is about the age of the Earth.

Even the oldest rocks would still have half of their radioactivity, and younger rocks would have more.

Thus, U-238 and Pb-206 are ideal isotopes for measuring the ages of rocks.

1. The metamorphic rocks are produced when the parent or the pre-existing rocks (whether sedimentary, igneous, or even metamorphic) are changed by pressure, heat, and the chemical activity of the fluids.  

When the prime changing factor is heat, generally due to direct contact, it may go through fundamental modification in recrystallization and texture is known as contact metamorphism. While regional metamorphism takes place when the minerals and texture of the rock are modified by pressure and heat.  

Metamorphic rocks form when heat and pressure transform existing rocks through contact or regional metamorphism. The volcanoes northwest of the Big Island of Hawaii are no longer erupting because they have moved away from the hotspot. To locate an earthquake's epicenter, data from a minimum of three seismic stations is required.

1). Metamorphic rocks are formed when existing rocks are transformed by heat and pressure. This process can occur through two main types of metamorphism: contact metamorphism and regional metamorphism.

2). Volcanoes on Hawaiian Islands:

The volcanoes on the Hawaiian islands northwest of the Big Island of Hawaii are no longer erupting because they have moved away from the hotspot in the Earth's mantle that supplies magma. As the Pacific Plate moves northwestward, the older volcanoes are carried away from the hotspot, becoming dormant.

3). Boiling Water:

When explaining how a pot of water boils, three terms are essential: radiation, conduction, and convection.

4). Finding Earthquake Epicenter:

A minimum of three seismic stations is needed to find the epicenter of an earthquake due to the process called triangulation. Each station records the time it takes for seismic waves to reach them, and by plotting circles with the quake's arrival time at each station, the intersection point of the three circles pinpoints the epicenter.

Answer is: a. it is determined from known oxidation state of an element within a compound determined.

Oxidation state (oxidation number) shows the degree of oxidation of an atom in a chemical compound.

For example, chlorate ion (ClO₃⁻) has negative charge.

One oxygen atom in this anion (negatively charged ion) has the oxidation number -2. There are three oxygen atoms in chlorate anion.

x + 3 · (-2) = -1.

x = -1 + 6.

x = +5; the oxidation number of chlorine.

The oxidation state of Cl (chlorine) in chlorate ion is +5.

Answer : Formation of yellow precipitate is the physical evidence that there has been a chemical reaction.

Explanation :

A chemical reaction happens when 2 or more substances chemically react with each other.

There are 4 evidences indicating that a chemical reaction has occurred which are mentioned below.

1. Change in color : On mixing, the reaction mixture can change color indicating that a chemical change may have occurred.

2. Formation of precipitate : A reaction in which a solid is formed on mixing 2 aqueous solutions is called as precipitation reaction. Here, the formation of solid indicates a chemical change.

ex. [tex]AgNO_{3} (aq) + NaCl (aq) \rightarrow AgCl (s) + NaNO_{3} (aq)[/tex]

In above reaction, on mixing the solutions, a white precipitate of AgCl is formed which indicates a chemical change.

3. Evolution of gas : A chemical change also occurs when a gas is evolved on mixing 2 substances.

ex. [tex]2HCl (aq) + Na_{2}CO_{3} (aq) \rightarrow 2NaCl (aq) + H_{2}O (l) + CO_{2} (g)[/tex]

In above reaction, CO2 gas is evolved and bubbles can be seen in the form of effervescence.

4. Change in temperature : Certain chemical reactions absorb or evolve heat. When a chemical reaction evolves heat, the temperature of the final reaction mixture increases and when it absorbs heat, the temperature decreases. This increase and decrease in temperature indicates a chemical change.

ex.  [tex]HCl (aq) + NaOH (aq) \rightarrow NaCl(aq) + H_{2}O (l)[/tex]

In above reaction, the final mixture becomes hot as the reaction releases heat. ( Exothermic)

Change in odor also indicates a chemical change.

For the given reaction, a yellow precipitate of PbI2 is getting formed.

Therefore formation of this precipitate is the physical evidence that there has been a chemical reaction.

Answer:

precipitate formation occurs

Explanation:

did usa test prep

Answer:

115.2 °C since melting point is an intensive property  

Step-by-step explanation:

The melting point of a substance does not depend on how much you have.

For example, the melting point of water is 0 °C, whether it is an ice cube from the refrigerator or in the frozen pond outside.

The freezing point of a substance is an intensive property.

Thus, the melting point of 100 g of sulfur is 115.2 °C because melting point in an intensive property.

B rises sharply on the right

The pattern which serves as a characteristic of a graph of exponential growth is that it B rises sharply on the right .

Exponential growth serves as a consistent growth rate that brings about rapid increase in growth as total growth numbers increase.

It do takes place when there is an instantaneous rate of change of a quantity with respect to time.

Learn more about Exponential growth at;

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equation Fe3O4=Fe+CO2 is an impossible reaction

Answer : The correct option is, The pH decreases.

Explanation :

As we know that,

pH : It is defined as the negative logarithm of hydrogen ion concentration.

Mathematically it is represented as :

[tex]pH=-\log [H^+][/tex]

According to the question, when the concentration of hydrogen ion increases then the value of pH decreases and the acidity of the solution also increases that means the solution is more acidic in nature.

Hence, if the hydrogen ion concentration increases, the pH decreases.

Answer:

The pH decreases

Explanation:

Hello,

pH is mathematically defined via:

[tex]pH=-log([H^{+} ])[/tex]

Since at the beginning, the concentration of hydride ion is 1e-2M, the pH is:

[tex]pH=-log(1x10^{-2} )=2.0[/tex]

If it is increased, lets suppose to 1.1e-2, the new pH turns out into:

[tex]pH=-log(1.1x10^{-2} )=1.96[/tex]

So the pH decreases, which means that the acidity increases as well.

Best regards.

The earth is inclined to the plane of its orbit by 23.5 degrees. Therefore for half the time in its earth on its orbit, the north pole will be inclined towards the sun. During this period, the pole receives six months of continuous sunshine. In the other half of the revolution around the sun, the north pole is tilted away from the sun hence receives darkness for 6 months.

Answer is: B. Energy transfer would occur between the copper bars and the surroundings.

Closed system is a physical system that does not allow transfer of mass and energy in or out of the system.

Open system is a physical system that does allow transfer of mass and energy in or out of the system, have input and output flows.

Thermal conductuction is the transfer of heat through physical contact. Thermal conduction is the transfer of heat by microscopic collisions of particles.

Heat spontaneously flows from a hotter to a colder body.

The correct answer is option 4, that is, a fewer number of particles of the sample will dissolve in 1 minute.  

This is mainly because usually the solubility and the rate of solubility of the salts in water enhances with the increase in temperature, that is, the more the temperature, the faster and higher will be the number of particles that the water can dissolve. Therefore, at 70 degree Celsius more particles will get dissolved in water in 1 minute than at 20 degree Celsius.  

Answer: its (4) a fewer number of particles of the sample will dissolve in 1 minute

Explanation:

got it right on my test

Answer: [tex]Cu(NO_3)_2[/tex] solution has blue color and [tex]Ni(NO_3)_2[/tex] solution has bright green color.

Explanation:

[tex]Cu(NO_3)_2(aq)\rightarrow Cu^{2+}(aq)(blue)+ NO_{3}^{1-}(aq)[/tex]

[tex]Cu(NO_3)2[/tex] in its aqueous solution gives blue color solution. Copper being transition metal and gives characteristic color in their in aqueous solution.

[tex]Ni(NO_3)_2(aq)\rightarrow Ni^{2+}(aq)(green)+ NO_{3}^{1-}(aq)[/tex]

[tex]Ni(NO_3)2[/tex] in its aqueous solution gives bright green color solution. Nickel is also a transition metal and gives characteristic color in their in aqueous solution.

Cu(NO3)2 solution shows a deep blue color due to the Cu²⁺ ions it contains, whereas Ni(NO3)2 solution generally appears greenish due to the Ni²⁺ ions. You can distinguish these solutions by their colors.

You can distinguish between a Cu(NO3)2 (copper(II) nitrate) solution and a Ni(NO3)2 (nickel(II) nitrate) solution by color. Specifically, Cu(NO3)2 solutions are typically characterized by a deep blue color due to the Cu²⁺ ions it contains.

On the other hand, Ni(NO3)2 solutions generally appear greenish, owed to the characteristic color of Ni²⁺ ions. Figures 19.40 and 18.36 show this difference -- while the copper nitrate solution shows a deep blue color, a nickel nitrate solution would appear more greenish.

Thus, by observing the color of the solutions, it is possible to distinguish between them based on the characteristic color patterns of their constituent ions.

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Answer : The concentration can be expressed as, 1.99 M, or 15.1(m/m)%, or 18(m/v)%

Solution : Given,

Volume of solution = 0.5 L = 500 ml        (1 L = 1000 ml)

Mass of solution = 596 g

Mass of oxalic acid, (solute) = 90 g

Molar mass of oxalic acid = 90.03 g/mole

First we have to calculate the concentration in terms of M(molarity).

Molarity : Molarity is defined as the number of moles of solute present in one liter of solution.

Formula used : [tex]M=\frac{w_{solute}}{M_{solute}\times V_s}[/tex]

where,

M = molarity of solution

[tex]w_{solute}[/tex] = mass of solute(oxalic acid)

[tex]M_{solute}[/tex] = molar mass of solute(oxalic acid)

[tex]V_s[/tex] = volume of solution(in liters)

Now put all the given values in this formula, we get

[tex]M=\frac{90g}{90.03g/mole\times 0.5L}=1.99mole/L=1.99M[/tex]

Now we have to calculate the concentration in terms of (m/m)%

(m/m)% : It is defined as the mass of solute present in mass of solution in grams.

Formula used : [tex](m/m)\%=\frac{w_{solute}}{w_s}\times 100[/tex]

where,

[tex]w_s[/tex] = mass of solution

[tex](m/m)\%=\frac{90g}{596g}\times 100=15.1%[/tex]

Now we have to calculate the concentration in terms of (m/v)%

(m/v)% : It is defined as the mass of solute present in one milliliter of solution.

Formula used : [tex](m/v)\%=\frac{w_{solute}}{V_s}\times 100[/tex]

where,

[tex]w_s[/tex] = mass of solution

[tex](m/m)\%=\frac{90g}{500ml}\times 100=18%[/tex]

Methylene blue indicates the presence of oxidizing agents because it is oxidized itself by these compounds. When electrons are stripped from methylene blue, the resulting molecule imparts a blue color to the solution--giving a clear sign of a chemical change.

Methylene blue appears blue because of its unique molecular structure with an extended system of conjugated pi bonds, which absorbs certain wavelengths of light in the non-blue spectrum. In its oxidized state, it is blue, and in its reduced form, it is colorless.

Methylene blue shows a blue color due to its unique chemical structure. It absorbs certain wavelengths of light within the blue region of the visible spectrum due to its extended system of conjugated pi bonds, i.e., alternate single and double bonds in its molecular structure. Methylene blue does not absorb blue light, but reflects it, making the compound appear blue to our eyes.

Additionally, Methylene blue is known for its reduction-oxidation properties. In an oxidized state, it is blue, while its reduced form is colorless. This means that the molecule can change its color based on whether it is gaining or losing electrons, a property that is utilized in many biological and research applications, including staining cells for microscope viewing and acting as an antidote for certain types of poisonings, like rotenone poisoning.

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Answer:

The volume of 3.25 grams of ammonia is 4.28 L

Explanation:

Step 1: Data given

Mass of ammonia = 3.25 grams

Molar mass of ammonia = 17.03 g/mol

Step 2: Calculate moles ammonia

Moles NH3 = mass NH3 / molar mass NH3

Moles NH3 = 3.25 grams / 17.03 g/mol

Moles NH3 = 0.191 moles

Step 3: Calculate volume of NH3

1 mol = 22.4 L

0.191 moles = 22.4 * 0.191 = 4.28 L

The volume of 3.25 grams of ammonia is 4.28 L

To find the volume of 3.25 g of ammonia, assuming an 8% solution with water-like density, we calculate the moles of ammonia and use the molarity to estimate the volume, which is approximately 40.7 mL.

To calculate the number of liters of ammonia in 3.25 g, we need to consider the density of ammonia. However, the initial question seems incomplete as it does not provide the concentration or density of ammonia directly. Instead, we are just provided a percentage which is typically used for solutions.

If we assume a solution of ammonia with a density similar to water, the number of liters can be estimated using the analytical concentration of an 8% ammonia by weight solution. Given this solution, ammonia has a concentration of 4.7 M (mol/L, assuming 1 L weighs 1000 g and 80 g of ammonia corresponds to 80 / 17 = 4.705882353 mol/L).

The number of moles of ammonia in 3.25 g can be calculated by dividing the mass by the molar mass of ammonia (17 g/mol):

n = mass / molar mass = 3.25 g / 17 g/mol = 0.1912 mol

Now, using the molarity (M), which is moles of solute per liter of solution (mol/L), we can find the volume V:

V = n / M = 0.1912 mol / 4.7 mol/L = 0.0407 L or 40.7 mL

Therefore, 3.25 g of an 8% ammonia solution corresponds to approximately 40.7 mL.