When magnesium ribbon reacts with steam, a solid called magnesium
oxide and hydrogen gas are formed. Which of the following is the correct
word equation?
O magnesium + hydrogen -> magnesium + water
magnesium + water -> magnesium oxide + hydrogen
O magnesium + water -> magnesium + hydrogen
O magnesium + magnesium oxide -> hydrogen + water

Answer:

Explanation:

Here, we want to identify the reducing and the oxidizing agent

The reducing agent is the one that undergoes oxidation while the oxidizing agent is the one that undergoes reduction

While oxidation refers to the loss of electrons, reduction is the gain of electrons

By looking at the componets that gained or loss electrons,we can idenify the oxidizing or reducing agent

From what we have in the guestion, sulfuric acid is the oxidiszing agent as it is the one that undergoes reduction.

Answer:

Know how many electrons it has

If you wanted to find the chemical element of an atom, you would need to know how many electrons it has. So the correct option is A.

Any compound that cannot be broken down into simpler chemicals by regular chemical processes is referred to as a chemical element or element. The building blocks of which all matter is made are called elements.

There are 118 chemical elements that are currently recognized. About 20% of them have only been created synthetically in the lab and are only known because they do not exist in nature or are only present in trace levels.

Of the known elements, 11 are gases under normal circumstances (hydrogen, nitrogen, oxygen, fluorine, chlorine, and the six noble gases), 2 are liquids (two more, cesium and gallium, melt at slightly above or around room temperature), and the remaining 7 are solids.

Compounds are made of a number of more complex substances that are formed when elements mix with one another. Nearly all conceivable compounds have been found, and there are likely millions more that have yet to be identified.

When two or more elements come together to create a compound, they lose their individual identities and the resultant substance exhibits properties that are very different from those of the original constituents.

Therefore the correct option is A

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Answer:

im pretty sure its b

Explanation:

When any substance converts to liquid then heat is required to break the intermolecular forces of attraction between the particles. In this process heat increase but temperature remains the same. The line along B represents the melting of unknown substance. Therefore the 72°C is melting point of the substance.

Phase transition is a process in which transition takes place from one state to another of a medium on changing temperature or pressure. Phase transition is a physical process as there is no breaking of old bond and forming of new bonds takes place.

During phase transition temperature remain constant as the extra heat that is given to the system that goes into breaking of intermolecular forces of attraction between the particles. So overall temperature remains same but heat keeps on increasing.

The line along B represents the melting of unknown substance. Therefore the 72°C is melting point of the substance.

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Answer:

185K

Explanation:

After the molecules mix, they reach a thermal equilibrium.....

Teq =(T1 + T2)/2 =(100+300)/2 =200K

since 185K is closer to 200K than the other options... Therefore the possible equilibrium temperature is 185K

We are given an initial temperature of the system, T1, as:

T1 = 300 K

After the divider is removed, the system will reach thermal equilibrium. According to the second law of thermodynamics, heat will flow from the hotter object to the colder object until the temperatures equalize.

This means the final temperature of the system after the divider is removed will be somewhere in between the initial temperatures of the two parts.

So considering the four answer choices:

A) 100 K - This is too low, the final temperature will be higher than 100K

B) 75 K - Also too low

C) 325 K - This is the initial temperature of one part, so the final temperature cannot be 325K

D) 185 K - This is a plausible final temperature in between 100K and 300K

Therefore, the answer is likely to be D) 185 K

In short, the key points are:

Heat will flow from the hotter to colder object until temperatures equalize

The final temperature will be somewhere in between the initial temperatures of the two parts

Answer choices A,B and C are too low or the same as one of the initial temperatures

Only D) 185K is a plausible intermediate temperature between 100K and 300K

Answer:

c

Explanation:

Answer:

Hard water is water that has high mineral content, Soft water is free from dissolved salts of such metals as calcium, iron, or magnesium

Explanation:

The east to west daily motions of stars, planets, the Moon, and the Sun are caused by the rotation of the Earth on its axis. The Earth and all the planets revolve around the Sun on circular orbits. This produces the change in constellations observed from one time of year to the next.

hope it helps..!!!

Answer:

Density, \(d=0.82\ g/cm^3\)

Explanation:

It is given that,

Mass of an unknown liquid, m = 20.5 g

The volume of unknown liquid is 25 mL

We need to find the volume of the brass object. Mass per unit volume of an object is called its density.

We know that, 1 mL = 1 cm³

So, 25 mL = 25 cm³

\(d=\dfrac{m}{V}\)

Putting the values, we get :

\(d=\dfrac{20.5\ g}{25\ cm^3}\\\\d=0.82\ g/cm^3\)

So, the density of this substance is \(0.82\ g/cm^3\)

Answer:

when a cold metallic is put in a water bath with cold water than the laws of thermodynamics and calorimetry suggests that both the solid and the liquid will engage in heat exchange until they attain equilibrium.

once they both are at equal temperature, no heat transfer will continue and the bodies will just stat in a packed atmosphere.

Compound is a group of same molecules, Element is a group of same atoms and mixture is combination of two or more pure substances.

What are Molecules ?

Molecules are the combination of two or more different atoms combine in a fixed ratio.

Molecules can be independently founded.

Atoms are always founded in combined state and does not occurs independently except rare earth elements which belongs to 18th group of periodic table.

Chemicals are taken in compound state But they undergo chemical reaction individually in molecular level.

Hence, Compound is a group of same molecules, Element is a group of same atoms and mixture is combination of two or more pure substances.

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The percent composition of calcium acetate is 29.89% calcium, 17.92% carbon, 4.52% hydrogen, and 47.67% oxygen.

To calculate the percent composition of calcium acetate (Ca(C2H3O2)2), you need to determine the total atomic mass of each element in the compound and divide it by the molar mass of the entire compound.
The atomic mass of calcium (Ca) is 40.08 g/mol, the atomic mass of carbon (C) is 12.01 g/mol, the atomic mass of hydrogen (H) is 1.01 g/mol, and the atomic mass of oxygen (O) is 16.00 g/mol. The molar mass of calcium acetate is:
1 Ca atom x 40.08 g/mol = 40.08 g/mol Ca
2 C atoms x 12.01 g/mol = 24.02 g/mol C
6 H atoms x 1.01 g/mol = 6.06 g/mol H
4 O atoms x 16.00 g/mol = 64.00 g/mol O
Total molar mass = 134.16 g/mol
To calculate the percent composition of each element:
% Ca = (40.08 g/mol Ca / 134.16 g/mol) x 100% = 29.89%
% C = (24.02 g/mol C / 134.16 g/mol) x 100% = 17.92%
% H = (6.06 g/mol H / 134.16 g/mol) x 100% = 4.52%
% O = (64.00 g/mol O / 134.16 g/mol) x 100% = 47.67%
Therefore, the percent composition of calcium acetate is 29.89% calcium, 17.92% carbon, 4.52% hydrogen, and 47.67% oxygen.

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1.78 grams of silver can be produced from 1.40 g silver nitrate and excess copper. The balanced chemical equation for the reaction of copper with silver nitrate (use cu2) is as follows: Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag

To determine how many grams of silver can be produced from 1.40 g of silver nitrate and excess copper, we first need to calculate the limiting reactant.

The stoichiometry of the reaction is such that 2 moles of silver nitrate react with 1 mole of copper to produce 2 moles of silver. The molar mass of silver nitrate is 169.87 g/mol while that of copper is 63.55 g/mol,

therefore, the number of moles of silver nitrate present in 1.40 g can be calculated as follows:Number of moles of silver nitrate = mass/molar mass= 1.40/169.87= 0.008240 molSimilarly, the number of moles of copper required to react with this quantity of silver nitrate is 0.004120 mol (half of the number of moles of silver nitrate).

Since there is an excess of copper, it will not limit the reaction and hence the limiting reactant is silver nitrate.To calculate the mass of silver produced, we use the molar mass of silver, which is 107.87 g/mol.Mass of silver produced = number of moles of silver x molar mass= 0.01648 x 107.87= 1.78 g

Therefore, 1.78 grams of silver can be produced from 1.40 g silver nitrate and excess copper.

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: PM2.5 is defined as the mass concentration of particles in the air less than or equal to 2.5 micrometers in diameter.Question 15: False, carbon dioxide (CO2) is not considered a criteria air pollutant.

Question 16: The closest answer is 50%, but the exact percentage is not provided in the question.Question 17: The term "photochemical smog" is most synonymous with ozone (O3), which is a criteria air pollutant.Question 18: True, attainment of ambient air quality standards requires that measured concentrations at all monitoring stations within an air district are below ambient air standards.

Question 14 asks about the definition of PM2.5. PM2.5 refers to particulate matter with a diameter less than or equal to 2.5 micrometers. It represents the mass concentration of particles suspended in the air, which are small enough to be inhaled into the respiratory system and can have adverse health effects.

Question 15 states whether carbon dioxide (CO2) is a criteria air pollutant. Criteria air pollutants are a set of pollutants regulated by environmental agencies due to their detrimental impact on air quality and human health. However, carbon dioxide is not considered a criteria air pollutant because it does not directly cause harm to human health or the environment in the same way as pollutants like ozone or particulate matter.

Question 16 asks about the percentage of carbon monoxide (CO) emissions from mobile sources in Santa Clara County. While the exact percentage is not provided in the question, the closest answer option is 50%. However, it is important to note that the precise percentage may vary depending on specific local conditions and emissions sources.

Question 17 inquires about the criteria air pollutant most synonymous with the term "photochemical smog." Photochemical smog is primarily associated with high levels of ground-level ozone (O3). Ozone is formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight, creating a hazy and polluted atmospheric condition.

Question 18 addresses the concept of "attainment" of ambient air quality standards. To achieve attainment, measured concentrations of pollutants at all monitoring stations within an air district must be below the established ambient air quality standards. This ensures that the air quality in the given area meets the required standards for protecting human health and the environment.

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Answer:

The osmotic pressure can be calculated using the Van't Hoff equation:Π = MRTwhere M is the molar concentration of the solute, R is the gas constant (0.0821 L atm K^-1 mol^-1), T is the temperature in Kelvin (273.15 K + 27.0°C = 300.15 K), and Π is the osmotic pressure in atmospheres.

Converting mmHg to atmospheres:

39.5 mmHg * 1 atm/760 mmHg = 0.052 atm

Rearranging the equation and solving for M:

M = Π / (RT) = 0.052 atm / (0.0821 L atm K^-1 mol^-1 * 300.15 K)

Next, we can use the molar mass to find the moles of solute:

moles = mass / molar mass = 1.80 g / molar mass

Finally, we can set the moles equal to the molar concentration and solve for molar mass:

M = moles / volume = moles / 0.500 L

moles = M * volume = 0.052 atm / (0.0821 L atm K^-1 mol^-1 * 300.15 K) * 0.500 Lmolar mass = mass / moles = 1.80 g / (moles)

Solving for molar mass gives a value of approximately 86 g/mol.

The molar mass of the non-electrolyte is 169.9 g/mol.

Osmotic pressure is a colligative property of a solution, which means it depends on the number of solute particles in the solution, not on their chemical nature. For a dilute solution of a non-electrolyte, the osmotic pressure is given by the following equation:

π = MRT

where π is the osmotic pressure, M is the molar concentration of the solute, R is the gas constant, and T is the temperature in Kelvin.

In this problem, we are given the mass of the non-electrolyte (1.80 g), the volume of the solution (500.0 mL), and the temperature (27.0 °C), and we are asked to find the molar mass of the compound.

First, we need to calculate the molar concentration of the solution:

M = n/V

where n is the number of moles of the solute and V is the volume of the solution. We can find n by dividing the mass of the solute by its molar mass:

n = m/M

where m is the mass of the solute (1.80 g). Substituting these values into the equation for molar concentration, we get:

M = (1.80 g / M) / (0.5000 L)

Solving for M, we get:

M = 0.07198 g/L

Next, we need to convert the temperature from Celsius to Kelvin:

T = 27.0 °C + 273.15 = 300.15 K

Finally, we can use the equation for osmotic pressure to solve for the molar mass (M) of the non-electrolyte:

π = MRT

M = π / RT = (39.5 mmHg) / (0.08206 L atm/mol K * 300.15 K)

M = 169.9 g/mol

Therefore, the molar mass of the non-electrolyte is 169.9 g/mol.

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One tube has a buffered solution + acid and the other tube has water + acid. To decide whether or not the solution is buffered, a simple pH test can be done. An acid-base indicator can be used to determine the pH of each solution.

A buffered solution is defined as a solution that can withstand minor changes in pH upon the addition of small amounts of an acid or base.

Consider the following steps:

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The required volume of 0.100 M H2SO4 solution to react with 10.0 g of NaOH is 50.0 mL.

This calculation involves the use of stoichiometry and the principles of limiting reagents to determine the volume of H2SO4 solution required to react with a given amount of NaOH. The balanced chemical equation for the reaction between NaOH and H2SO4 is 2NaOH + H2SO4 → Na2SO4 + 2H2O. From the equation, it can be seen that two moles of NaOH react with one mole of H2SO4.

The molar mass of NaOH is used to convert its mass to moles, and the mole ratio between NaOH and H2SO4 is used to calculate the number of moles of H2SO4 required to react with the given amount of NaOH. Finally, the molarity of the H2SO4 solution is used to calculate the required volume of the solution. This problem falls under the sub-topic of stoichiometry in chemistry, which deals with the quantitative relationships between reactants and products in a chemical reaction.

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The kind of material used to bake food will influence how much energy is required to heat it up and how quickly it cools. Due to the fact that metal conducts heat more effectively than glass, heating up metal pans often takes longer than heating up glass ovenware.

This implies that the metal absorbs heat from the oven more rapidly and effectively, needing more energy to attain the appropriate temperature. However, oven-safe glass will cool down more quickly than metal.

This is due to the fact that glass is a poor heat conductor, which means it takes more time for the heat to be absorbed by the glass. The glass will shatter after the dish is cooked and the heat is turned off.As the heat takes longer to dissipate, the metal cools down more quickly than the other materials.

In conclusion, glass cools more quickly than metal and requires less energy to heat up than oven-safe metal. This is because metal absorbs heat from the oven more rapidly and effectively than glass since metal is a stronger heat conductor than glass.

However, because glass is a poor conductor of heat, it takes longer for the food to cook and the heat to be absorbed. The glass cools down more quickly than the metal when the heat is gone.

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\(2CO + O_{2} ---- > 2CO_{2}\\2Na + 2H_{2} O---- > 2NaOH + H_{2} \\2P + 3Cl_{2} ------ > 2PCl_3} \\Pb_{3} O_{4} +HNO_{3} ------ > 2Pb(NO3)_{2} + H_{2} O + PbO_{2}\)

A reaction equation is a representation of the reaction that takes place in the reaction vessel. We know that a reaction equation is balanced when the number of atoms of each of the elements is the same on both sides of the reaction equation.

We can achieve the balancing of the reaction equations by the process of an atom count. We try to find out if we have the same number of atoms on both sides of the reaction equation by carrying out a literal counting of the atoms.

Let us now attempt to write the balanced reaction equation in each case;

\(2CO + O_{2} ---- > 2CO_{2}\\2Na + 2H_{2} O---- > 2NaOH + H_{2} \\2P + 3Cl_{2} ------ > 2PCl_3} \\Pb_{3} O_{4} +HNO_{3} ------ > 2Pb(NO3)_{2} + H_{2} O + PbO_{2}\)

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The value in centimeters squared is 20.32 cm^2.

A conversion factor is a ratio of equivalent values used to convert a quantity from one unit to another. It is a factor that can be used to multiply or divide the original quantity to obtain the converted quantity.

If 1 in^2 = 6.45 cm^2

Then; 3.15in^2  = 20.32 cm^2

In general, the conversion factor must be chosen carefully to ensure that the units are consistent and that the proper units are used for the physical quantities being measured.

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Answer: m=0.2699g

Explanation:

n=m/M   (n=moles, m=mass, M=molar mass)

nxM=m

0.01x26.99=m    (26.99=molar mass of aluminium (seen on periodic table))

m=0.2699g

Explanation:

Find moles first

moles = number of particles/ 6×10^23

= 7.52 ×10^25 / 6×10^23

=125.33

calculate molar mass

(1×14) +(3×1) =17

convert to mass

mass= moles × molar mass

=125.33 × 17

=2130.67g

This is a pretty big value usually it's smaller but I'd assume it's because the number of particles was large.

In the Ostwald process, 4 molecules of ammonia and 5 molecules of oxygen react to produce 4 molecules of nitric oxide and 6 molecules of water.

The platinum-rhodium gauze catalyst is used in the first step of the Ostwald process to catalyze the oxidation of ammonia with oxygen to produce nitric oxide and water. The catalyst helps to lower the activation energy of the reaction and increase the rate of reaction.

The Ostwald process is a chemical process used to produce nitric acid (HNO3) from ammonia (NH3) and oxygen (O2). The process involves two main steps. In the first step, ammonia is oxidized with oxygen to produce nitric oxide (NO) and water (H2O) according to the following reaction:

4NH3 + 5O2 → 4NO + 6H2O

This reaction is exothermic and is typically carried out in a catalytic reactor at temperatures between 800°C and 900°C using a platinum-rhodium gauze catalyst.

In the second step, the nitric oxide is further oxidized with air to produce nitrogen dioxide (NO2) which is then absorbed in water to produce nitric acid:

2NO + O2 → 2NO2

3NO2 + H2O → 2HNO3 + NO

The nitrogen dioxide (NO2) is typically produced by passing the nitric oxide (NO) through a bed of vanadium oxide catalysts and then mixing it with air.

The Ostwald process is an important industrial process for the production of nitric acid, which is used in the production of fertilizers, dyes, and other chemicals.

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Answer: Digestive enzymes play a key role in breaking down the food you eat. These proteins speed up chemical reactions that turn nutrients into substances that your digestive tract can absorb. Your saliva has digestive enzymes in it

Explanation:

Answer:

a. pH = 2.22.

b. [H+] = 2.588 x 10⁻⁴ mol/L.

Explanation:

Acids and Bases => Calculating pH of Acids and Bases.

As we saw before, the formulas to find the pH based on the hydrogen ion concentration [H+], and to find the hydrogen ion concentration [H+] based on the pH are the following, respectively:

So let's see each case:

a. To find the pH of an H+ concentration of 6.02 x 10⁻³ mol/L we use the pH formula:

The answer would be that the pH is 2.22.

b. To find the H+ concentration of a pH of 3.587, we use the [H+] formula:

The answer would be that the hydrogen ion concentration [H+] = 2.588 x 10⁻⁴ mol/L.

Answer:

The amount of time required for each radioactive atom to decay halfway.

Explanation:

In radioactivity, which is the spontaneous emission of radiations from the nucleus of an unstable atom, each atom has a specific term called HALF-LIFE and is denoted by t1⁄2. Half-Life of an atom represents the amount of time it takes the nucleus of that atom to decay by half.

Therefore, based on the definitions given in the question, "The amount of time required for each radioactive atom to decay halfway" best describes HALF-LIFE.

- The first definition is wrong because it is NOT HALF THE AMOUNT OF TIME but half the amount of the atom while the second definition is wrong because it is NOT ALL THE ATOMS but a specific atom. Each atom has its own specific half-life.

Answer:

1.91×1021/6.023×10^23

Explanation:

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Answer: The percent yield is, 93.4%

Explanation:

First we have to calculate the moles of Na.

\(\text{Moles of Na}=\frac{\text{Mass of Na}}{\text{Molar mass of Na}}=\frac{41.9g}{23g/mole}=1.82moles\)

Now we have to calculate the moles of \(Br_2\)

\({\text{Moles of}Br_2} = \frac{\text{Mass of }Br_2 }{\text{Molar mass of} Br_2} =\frac{30.3g}{160g/mole}=0.189moles\)

\({\text{Moles of } NaBr} = \frac{\text{Mass of } NaBr }{\text{Molar mass of } NaBr} =\frac{36.4g}{103g/mole}=0.353moles\)

The balanced chemical reaction is,

\(2Na(s)+Br_2(g)\rightarrow 2NaBr\)

As, 1 mole of bromine react with = 2 moles of Sodium

So, 0.189 moles of bromine react with = \(\frac{2}{1}\times 0.189=0.378\) moles of Sodium

Thus bromine is the limiting reagent as it limits the formation of product and Na is the excess reagent.

As, 1 mole of bromine give = 2 moles of Sodium bromide

So, 0.189 moles of bromine give = \(\frac{2}{1}\times 0.189=0.378\) moles of Sodium bromide

Now we have to calculate the percent yield of reaction

\(\%\text{ yield}=\frac{\text{Actual yield}}{\text{Theoretical yield}}\times 100=\frac{0.353 mol}{0.378}\times 100=93.4\%\)

Therefore, the percent yield is, 93.4%