The speed of a wave on a guitar string is 100 m/s, and the frequency is 1,000 Hz. what is the wavelength of the wave?

There are two main ways to describe the location of an object:

1. Using a reference point

A reference point is a fixed point in space with respect to which the relative position or distance of an object is compared. For example, if we say that a book is on the table, we are using the table as a reference point.

2. Using cardinal directions

Cardinal directions are the four main compass directions: north, south, east, and west. We can use cardinal directions to describe the location of an object relative to another object or to a fixed point on Earth, such as the North Pole.

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Complete question:

How can we describe the location of an object?​

Answer:

A) pH = 2.8

B) pH = 5.5

C) pH = 8.9

D) pH = 13.72

Explanation:

a) [H⁺]  = 1.6 × 10⁻³ M

pH = -log [H⁺]

pH = -log [1.6 × 10⁻³ ]

pH = 2.8

b) [H⁺]  = 3 × 10⁻⁶

pH = -log [H⁺]

pH = -log [3 × 10⁻⁶ ]

pH = 5.5

c) [OH⁻] = 8.2 × 10⁻⁶

pOH = -log[OH]

pOH = -log[8.2 × 10⁻⁶]

pOH = 5.1

pH + pOH = 14

pH = 14 - pOH

pH = 14 - 5.1

pH = 8.9

d) [OH⁻] = 0.53 M

pOH = -log[OH]

pOH = -log[0.53]

pOH = 0.28

pH + pOH = 14

pH = 14 - pOH

pH = 14 - 0.28

pH = 13.72

Answer:

The answer is choice (4) 268 g.

Explanation:

To find this answer you have to go to the reference table, using Table G, and go to KNO3 at 70°C. Find out how many grams saturate potassium nitrate (134 g). Then you double it (268 g ) because it's asking for grams at 200 grams of water.

The molecular formula for the compound is  [tex]C_{3} H_{6}[/tex]

Explanation:

As with all of these problems, we assume 100 g of an unknown compound.

And thus, we determine the elemental composition by the given percentages.

Moles of carbon = 85.64 / 12.011

                            = 7.13 mol.

Moles of hydrogen = 14.36 / 1.00794

                               = 14.25 mol.

There are 2 moles of hydrogen per mole of carbon. And thus the empirical formula is CH[tex]_{2}[/tex].

And molecular formula = n × (empirical formula)

Thus, 42.08 = n × (12.011 + 2 × 1.00794)

And thus n = 3, and molecular formula = [tex]C_{3} H_{6}[/tex]

Answer:

The number of molecules in 14.0g of [tex]NO{_2}[/tex] is 1.806* 10^23

Explanation:

We were given;

Mass = 14.0g of [tex]NO{_2}[/tex]

First of all, we will calculate the molecular mass(MM) of [tex]NO{_2}[/tex]

Atomic number of Nitrogen, N=14  

Atomic number of Oxygen, O=16

MM of NO_2 = (14+{16*2})

MM of NO_2 = (14+32) = 46g/mol

Also, we find the number of moles in [tex]NO{_2}[/tex] using the formula below;

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molecular mass}}

\text{Number of moles}=\frac{14}{46}

\text{Number of moles}=0.3moles

Nitrogen dioxide, [tex]NO{_2}[/tex] therefore has 0.3moles.

In Chemistry, we know 1\text{ mole}=6.022\times 10^{23}\text{ molecules}

So, 0.3\text{ mole}=6.022\times 10^{23}\times 0.3\text{ molecules}

0.3\text{ mole}=1.806\times 10^{23}\text{ molecules}

Therefore, The number of molecules in 14g of [tex]NO{_2}[/tex] is 1.806 × 10^23

To determine the number of molecules in 14.0 g of NO2, convert the mass to moles using the molar mass of NO2, then use Avogadro's number to convert moles to molecules, we get answer 1.832 x 1023 molecules.

To determine the number of molecules in 14.0 g of NO2, we need to convert the mass of NO2 to moles. The molar mass of NO2 is 46.01 g/mol. Using the formula:

       Number of moles = Mass (g) / Molar mass (g/mol)

We can calculate:

       Number of moles = 14.0 g / 46.01 g/mol = 0.304 mol

Next, we need to use Avogadro's number to convert the number of moles to the number of molecules. Avogadro's number is approximately 6.022 x 1023 molecules/mol. Using the formula:

       Number of molecules = Number of moles × Avogadro's number

We can calculate:

       Number of molecules = 0.304 mol × 6.022 x 1023 molecules/mol = 1.832 x 1023 molecules

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Answer:

To react with 0.5 moles of zinc 1 mole of hydrochloric acid is required

Explanation:

Given data:

Number of moles of HCl = ?

Number of moles of Zn = 0.50 mol

Chemical equation:

Zn + 2HCl  → H₂ + ZnCl₂

Now we will compare the moles of zinc and HCl.

                       Zn       :        HCl

                         1        :            2

                       0.50   :         2×0.5 = 1 mol

So, to react with 0.5 moles of zinc 1 mole of hydrochloric acid is required.

To react with 0.50 moles of Zn, 1.0 mole of HCl is required according to the stoichiometry of the balanced chemical equation.

To determine how many moles of HCl are needed to react with 0.50 moles of Zn, we look at the balanced chemical equation:

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

According to the stoichiometry of the reaction, 1 mole of Zn reacts with 2 moles of HCl. Therefore, to react with 0.50 moles of Zn, we would need double that amount of HCl, which is 1.0 mole of HCl.

Answer:

none of the options are correct

Explanation:

For cm3

1L = 1000cm3

40L = 40 x 1000 = 40000cm3

For m3

1L = 0.001m3

40L = 40 x 0.001 = 0.04m3

For mL

1L = 1000mL

40L = 40 x 1000 = 40000mL

From the calculations above, none of the options are correct

Answer:

n = 1.9 ×10⁻⁵ mol

Explanation:

Given data:

Volume of hydrogen gas = 455 mm

Pressure of hydrogen gas = 101.3 kpa

Temperature = 29.1°C

Partial pressure of water vapor = 4.0 kpa

Number of moles of hydrogen gas = ?

Solution:

First of all we will convert the units.

Pressure of hydrogen gas = 101.3 kpa= 101.3/101 =  1 atm

Partial pressure of water vapor = 4.0 kpa = 4.0/ 101 = 0.04 atm

Temperature = 29.1 + 273 = 302.1 K

Volume of hydrogen gas = 455 / 1×10⁶ = 0.000455 L

Now we will calculate the total pressure.

Total pressure = Partial pressure of hydrogen gas + partial pressure of water vapors

Total pressure = 1 atm + 0.04 atm

Total pressure = 1.04 atm

Now we will calculate the number of moles;

PV = nRT

n = PV/RT

n =  1.04 atm × 0.000455 L / 0.0821 atm.L / mol.K × 302.1 K

n = 0.00047 /24.80/mol

n = 1.9 ×10⁻⁵ mol

Answer:

First, calculate the partial pressure of hydrogen by subtracting the total pressure of the hydrogen–water vapor mixture from the partial pressure of water vapor:

101.3 kPa − 4.0 kPa = 97.3 kPa.

Convert the temperature to kelvins:

29.1°C + 273.15 = 302.25 K.

Convert milliliters to liters by dividing by 1,000 to get 0.455 L.

Since the pressure is in kilopascals, use the R value 8.314 .

Now substitute the known values into the ideal gas equation:

n =  

n =  

n =  

n = 0.0176176 mol

n = 0.0176 mol

Explanation:

PLATO ANSWER!

1.35 litres is the volume will the sample have if the pressure changes to 1.50 atm while the temperature is increased to 322 K.

Explanation:

Data given:

initial volume in the sample pf gas V1 = 1.42 L

initial temperature of the sample of gas T1 = 293 K

Initial pressure of the gas P1 = 1.30 atm

final pressure of the sample of gas  P2= 1.50 atm

final temperature of the sample of gas T2 = 322 K

Final volume V2 = ?

following formula is used:

[tex]\frac{P1V1}{T1}[/tex] = [tex]\frac{P2V2}{T2}[/tex]

V2 = [tex]\frac{P1V1T2}{P2T1}[/tex]

putting the values in the equation:

V2 = [tex]\frac{322 X 1.42 X 1.30}{1.50 X 293}[/tex]

   = 1.35 Litre is the volume

When pressure and temperature of the gas is changed the volume becomes 1.35 litres.

At high temperature the gas would diffuse out as the pressure increases and at extremely low temperature the solid becomes compact.

Explanation:

The states of matter largely depends on the temperature. Any substance when crosses the threshold temperature its phase changes.

When temperature is low the motion of molecules is also low and internal energy also gets low. Solid have tendency of settling in low energy level and have highly compact molecules. At low temperature the solid would compress as molecules would be highly condensed.

Gas in the nature has its molecules quite far apart in matter. According to Kinetic theory of gases the increase in temperature causes rapid collisions of the gas molecule as the kinetic energy of molecules increases. The greater force of collision would cause increase in pressure of the container and increased diffusion rate.

Final answer:

Solids remain solid but with reduced molecular vibration at extremely cold temperatures, and gases at extremely hot temperatures can expand, increase in pressure, or even form a plasma by breaking chemical bonds.

Explanation:

When a solid is exposed to extremely cold temperatures, it will remain solid because solids are the most stable state of matter at low temperatures. However, the kinetic energy of the molecules within the solid decreases further, which means the molecules vibrate less. In some cases, if the solid is cooled to near absolute zero, it is theorized that molecular movement would cease entirely, and the traditional differences between solids, liquids, and gases would no longer be apparent.

Conversely, when a gas is exposed to extremely hot temperatures, its molecules move more rapidly due to increased kinetic energy, impacting each other and the container with greater force. This can cause the gas to expand or increase in pressure. If the temperature is high enough to break chemical bonds within the molecules, the gas may dissociate into its atomic components or ionize, creating a plasma, which is sometimes referred to as the fourth state of matter.

Additionally, at extremely high temperatures, such as above 1000°C and pressures above 5 atm, a substance may enter a state known as a supercritical fluid, where it exhibits properties of both liquids and gases and does not have a distinct phase transition between liquid and gaseous states.

Answer:

0.454moles

Explanation:

Calculate the molar mass of AgBr

Ag=108

Br=80

Molar mass= 108+80

Molar mass=188g/mol

It's mole to gram question

2moles of Na2S2O3= 188g of AgBr

X moles of Na2S2O3=42.7g of AgBr

Cross multiply

188x=2×42.7

X= 85.4/188

X=0.454moles

Acceleration of the object is 8.75 m/s² and average velocity is 32.5 m/s

Explanation:

Acceleration of the object = Change in velocity/Time

                                            = 50 - 15/4 = 35/4 = 8.75 m/s²

                                     = 15 + 50/2 = 65/2 = 32.5 m/s

The acceleration of the object is 8.75 m/s², and assuming constant acceleration, the average velocity is 32.5 m/s.

To calculate the acceleration of an object when the velocity changes from 15 m/s to 50 m/s over a time interval of 4 s, we can use the formula for acceleration (a), where acceleration equals the change in velocity (Δv) divided by the change in time (Δt):

a = Δv / Δt

The change in velocity is the final velocity minus the initial velocity. Thus, Δv = 50 m/s - 15 m/s = 35 m/s. The time interval is Δt = 4 s.

a = 35 m/s / 4 s = 8.75 m/s²

The average velocity during this interval can be calculated by taking the sum of the initial and final velocities and dividing by two, assuming the acceleration is constant. Therefore, the average velocity (vavg) is:

vavg = (initial velocity + final velocity) / 2

vavg = (15 m/s + 50 m/s) / 2 = 32.5 m/s

Answer:

1.008 L

Explanation:

To solve this question you need to know the equation for the reaction. The equation for the reaction will be:

2 AlCl3 + 3 F2 → 2 AlF3 + 3 Cl2

We have excess fluorine so aluminum chloride will be the limiting reagent of the reaction. The coefficient of aluminum chloride is 2 while the coefficient of chlorine gas is 3. If the molecular mass of the aluminum chloride is 133.34 g/mol then the number of chlorine gas made in moles will be:

4g/ (133.34 g/mol) * (3/2)= 0.045 moles

Assuming the reaction happens in STP, the volume will be: 0.045 moles * 22.4 L/mol= 1.008 L

1.008 liters of chlorine gas are produced from the reaction of 4.00 grams of aluminum chloride with fluorine.

To determine how many liters of chlorine gas are produced when 4.00 grams of aluminum chloride reacts with excess fluorine, we start with the balanced chemical equation for the reaction:

2 AlCl₃ (s) + 3 F₂ (g) → 2 AlF₃ (s) + 3 Cl₂ (g)

Step 1: Calculate the moles of aluminum chloride (AlCl₃).

Step 2: Use stoichiometry to figure out the moles of chlorine gas (Cl₂) produced.

Step 3: Convert moles of Cl₂ to liters using the ideal gas law under standard conditions (1 mole gas = 22.4 L at STP).

Thus, 4.00 grams of aluminum chloride reacting with excess fluorine produces approximately 1.008 liters of chlorine gas.

Answer:

B electrons because Valence electrons of the elements in the bond are shared. The gain , loss , or sharing of electrons occurs in every chemical bond.

Answer:

positive one (+1)

Explanation:

sodium having atomic mass is twenty three (23) and atomic number is eleven (11).

Sodium atom having only one electron in it's outer most shell and it is easy for atom to lose this electron from outer most shell to make itself stable.

So after losing this electron positive charge on the upper right side of the atom will occur with the number of electron lose that is Na+1 .

Answer:

divide by molar mass (12.01 g)

Explanation:

To find the number of moles of the carbon, divide by molar mass (12.01 g).

The number of moles of a substance is given as;

           Number of moles  = [tex]\frac{mass}{molar mass}[/tex]

To solve this problem;

  since mass of carbon  = 45g

                Number of moles  = [tex]\frac{45}{12.01}[/tex]   = 3.75moles

Answer:

3.35 moles.

Explanation:

Hey there!

2 moles will be produced.

In N₂ there are 2 nitrogen atoms. In NH₃ there is 1 nitrogen atom.

So, there will be twice as many moles produced because there will be twice as many molecules.

Hope this helps!

Answer: m = 471 g CaCO3

Explanation: From the balanced equation, convert the moles of Na2CO3 to moles of CaCO3 using the mole ratio from the equation. Then convert miles of CaCO3 to mass using the molar mass of CaCO3.

Solution attached.

Rounding to an appropriate number of significant figures, the mass of calcium carbonate produced from 4.71 moles of sodium carbonate is approximately 471.2 grams.

To find the mass of calcium carbonate (CaCO₃) produced from 4.71 moles of sodium carbonate (Na₂CO₃), we need to use stoichiometry and the balanced chemical equation provided.

From the balanced chemical equation:

1 mole of Na₂CO₃ produces 1 mole of CaCO₃.

Therefore, to find the moles of CaCO₃ produced, we simply use the stoichiometric ratio:

Moles of CaCO₃ = 4.71 moles of Na₂CO₃

Now, we need to find the molar mass of CaCO₃ to convert moles to grams. The molar mass of CaCO₃ is:

Molar mass of CaCO₃ = (1 × atomic mass of Ca) + (1 × atomic mass of C) + (3 × atomic mass of O)

Molar mass of CaCO₃= (1 × 40.08 g/mol) + (1 × 12.01 g/mol) + (3 × 16.00 g/mol)

Molar mass of CaCO₃ = 40.08 g/mol + 12.01 g/mol + 48.00 g/mol

Molar mass of CaCO₃ = 100.09 g/mol

Now, we can calculate the mass of CaCO₃ produced:

Mass of CaCO₃ = Moles of CaCO₃ × Molar mass of CaCO₃

Mass of CaCO₃ = 4.71 moles × 100.09 g/mol

Mass of CaCO₃= 471.2439 g

Rounding to an appropriate number of significant figures, the mass of calcium carbonate produced from 4.71 moles of sodium carbonate is approximately 471.2 grams.

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Answer:

The answer is B) No.

Explanation:

The equation balanced is:

2 FeCl₃ + 3 MgO → Fe₂O₃ + 3 MgCl₂

Equation balancing can be done by "trial and error" or by algebraic method.

In this way the equation is balanced on both sides having:

2 atoms of Fe, 6 of Cl, 3 of Mg and 3 of 0.

Final answer:

The chemical equation FeCl₃ + MgO → Fe₂O₃ + MgCl₂ is not balanced due to unequal numbers of iron, chlorine, and oxygen atoms on the reactant and product sides. The balanced equation would be 2FeCl₃ + 3MgO → Fe₂O₃ + 3MgCl₂.

Explanation:

The student's equation, FeCl₃ + MgO → Fe₂O₃ + MgCl₂, is not balanced. To determine whether a chemical equation is balanced, we must ensure that there are equal numbers of each type of atom on both the reactant and product sides. Let's count the atoms of each element in the reactants and products:

As we can see, the numbers do not match for iron and chlorine, as well as oxygen. Thus, the equation must be balanced by adjustion coefficients to equalize the number of atoms for each element on both sides. The balanced equation would be 2FeCl₃ + 3MgO → Fe₂O₃ + 3MgCl₂.

Answer:

The number of neutrons effects the mass

Explanation:

The mass of siderite (FeCO3) that contains 1.0×10^3kg of iron can be calculated using the proportion of iron in siderite. The calculation shows that approximately 2.11×10^3kg of siderite contains 1.0×10^3kg of iron, to two significant figures.

To calculate the mass of the siderite (FeCO3) compound containing 1.0×10^3kg of iron (Fe), we first need to determine the molar mass of siderite. The molar mass of Fe is 55.845 g/mol, carbon (C) is 12.01 g/mol, and oxygen (O) is 16.00 g/mol. Since there are three oxygen atoms in siderite, the total molar mass of siderite is 55.845 g/mol (Fe) + 12.01 g/mol (C) + 3(16.00 g/mol) (O) = 115.855 g/mol.

Next, use the proportion of iron in siderite to calculate the mass of siderite that would contain 1.0×10^3kg of iron. Given that the proportion of iron in siderite is the molar mass of Fe divided by the molar mass of siderite (55.845/115.855), we can set up a proportion: (1.0×10^3kg Fe / x kg siderite) = (55.845 g / 115.855 g). Solving for x gives us the mass of siderite containing 1.0×10^3kg of iron, approximately 2.11×10^3kg to two significant figures.

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To calculate the mass of FeCO3 (siderite) that contains 1.0×10^3kg of iron, we need to determine the molar mass of FeCO3 and then use stoichiometry to convert the mass of iron to the mass of FeCO3. The mass of FeCO3 is approximately 2.06×10^3 kg.

To calculate the mass of FeCO3 (siderite) that contains 1.0×10^3kg of iron, we need to determine the molar mass of FeCO3.

The molar mass of FeCO3 can be calculated by adding up the atomic masses of its constituent elements: Fe (55.8 g/mol), C (12.0 g/mol), and O (16.0 g/mol).

Therefore, the molar mass of FeCO3 is 55.8 + 12.0 + (3 * 16.0) = 115.8 g/mol.

To convert the mass of iron (1.0×10^3 kg) to the mass of FeCO3, we can use the formula:

Mass of FeCO3 = (1.0×10^3 kg of iron) * (115.8 g/mol FeCO3) / (55.8 g/mol Fe)

Calculating this expression gives us:

Mass of FeCO3 = 2.06×10^3 kg

Therefore, the mass of FeCO3 that contains 1.0×10^3 kg of iron is approximately 2.06×10^3 kg.

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Answer:

Mass of water = 21.6 g

Explanation:

Given data:

Mass of C₂H₆ = 15 g

Mass of O₂ = 45 g

Mass of water produced = ?

Solution:

Chemical equation:

2C₂H₆ + 7O₂     →       4CO₂ + 6H₂O

Number of moles of C₂H₆:

Number of moles = mass/ molar mass

Number of moles = 15 g/ 30 g/mol

Number of moles = 0.5 mol

Number of moles of O₂ :

Number of moles = mass/ molar mass

Number of moles = 45 g/ 32 g/mol

Number of moles = 1.4 mol

Now we will compare the moles of C₂H₆ and O₂ with H₂O.

                           C₂H₆           :                H₂O

                             2               :                  6

                           0.5              :          6/2×0.5 = 1.5

                            O₂              :                H₂O

                             7               :                  6

                           1.4               :           6/7×1.4 = 1.2

The number of moles of water produced by  oxygen are less so it will limiting reactant.

Mass of water produced:

Mass = number of moles × molar mass

Mass = 1.2 mol × 18 g/mol

Mass = 21.6 g

Answer:

Percent yield = 57%

Explanation:

Given data:

Number of moles of propane = 4.50 mol

Number of moles of carbon dioxide = 7.64 mol

Percent yield = ?

Solution:

Chemical equation:

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Now we will compare the moles of propane and carbon dioxide.

                            C₃H₈            :            CO₂

                                 1               ;                3

                                  4.50        :              3×4.50 = 13.5 mol

Percent yield:

Percent yield = actual yield / theoretical yield × 100

Percent yield =  7.64 mol / 13.5 mol × 100

Percent yield = 0.57× 100

Percent yield = 57%

Final answer:

To find the number of moles of Hg produced from 34.0g of HgO, divide the mass of HgO by its molar mass and use the stoichiometric relationship from the decomposition equation, resulting in 0.157 moles of Hg.

Explanation:

The question is how many moles of Hg (mercury) will be produced from 34.0g of HgO (mercury(II) oxide). To answer this, we need to use the concept of mole-mass stoichiometry. The molar mass of HgO is approximately 216.59 g/mol. First, you calculate the moles of HgO using its molar mass:

Number of moles = mass (g) / molar mass (g/mol).

Then, based on the balanced chemical equation for the decomposition of HgO, which is 2 HgO (s) → 2 Hg (l) + O2 (g), we see that the molar ratio of Hg to HgO is 1:1. Therefore, the moles of Hg produced will be equal to the moles of HgO that decomposed.

Here is the calculation:

In conclusion, 34.0g of HgO will produce 0.157 moles of Hg when decomposed.

Answer:

C―O is more polar.

Explanation:

Based on electronegativity values, C―O bond is the most polar one in the above options. Polarity of substance is depend on difference of electronegativity values between bonded atoms. Those atoms having high difference of electronegativity values are more polar as compared to those having less difference of electronegativity values. Electronegativity value of C―O bond is 0.89.

Answer: The molar mass of the vapor comes out to be 43.83 g/mol. This problem is solved by using ideal gas equation. The ideal gas equation is shown below

[tex]\textrm{PV} =\textrm{nRT}[/tex]

Explanation:

Volume of gas = V = 247.3 mL  

V = 0.2473 L

Pressure of gas = P = 745 mmHg

1 atm = 760 mmHg

[tex]\textrm{P} = \displaystyle \frac{745}{760} \textrm{ atm} = 0.98026 \textrm{ atm}[/tex]

Temperature of gas = T = 100[tex]^{\circ}C[/tex] = 373 K

Given mass of gas = m = 0.347 g

Assuming molar mass of gas to be M g/mol

Assuming the gas to be an ideal gas, the ideal gas equation is shown below

[tex]\textrm{PV} =\textrm{nRT}[/tex]

Here, n is the number of moles of gas and R is the universal gas constant.

[tex]\textrm{PV} =\textrm{nRT} \\\textrm{PV} = \displaystyle \frac{m}{M}\textrm{RT} \\0.98026 \textrm{ atm}\times 0.2473 \textrm{ L} = \displaystyle \frac{0.347 \textrm{ g}}{M}\times 0.0821 \textrm{ L.atm.mol}^{-1}.K^{-1}\times 373 \textrm{ K} \\M = 43.83 \textrm{ g/mol}[/tex]

Hence, the molar mass of the vapor comes out to be 43.83 g/mol

Answer:

3. 049g

Explanation:

Molar mass of Ca = 40

Molar mass of Cl = 35.5

H = 1, O =16

Molar mass of CaCl2.9H20 = [40 + (35.5*2) + (9*18)]

CaCl2.9H20 = 273g/mol

Molar mass of CaCl2 = 40 + (35.5*2) = 111g/mol

111g of CaCl2 is present in 273g of CaCl2.9H20

Xg of CaCl2 is present in 7.5g of CaCl2.9H20

X = (7.5*111) / 273

X = 3.049g

Final answer:

To find the quantity of pure CaCl₂ in 7.5 g of CaCl₂•9H₂O, you need to calculate the molar masses of both the hydrated and anhydrous forms, find the number of moles in 7.5 g, and then convert this to grams of pure CaCl₂.

Explanation:

To determine the quantity of pure CaCl₂ in 7.5 g of CaCl₂•9H₂O, we first need to calculate the molar mass of the hydrated compound and then the molar mass of anhydrous CaCl₂. After that, using stoichiometry, we find out how many moles of the hydrated compound we have in 7.5 g and convert this to the mass of anhydrous CaCl₂.

The quantity of pure CaCl₂ in 7.5 g of CaCl₂•9H₂O is therefore approximately 3.05 g.