If there are 40 mol of NBr3 and 48 mol of NaOH, what is the excess reactant?

A) N2
B) NBr3
C) NaOH
D) HOBr

To identify the metal of the cube, calculate the cube's density by dividing its mass (15.4g) by its volume (1.728 cm³), which gives a density of approximately 8.91 g/cm³. This density can be compared to known densities to determine the cube's metal type.

The identity of a metal cube can be determined using its mass and volume to calculate its density, which can then be compared to known densities of various metals. A cube with each side measuring 1.2 cm has a volume given by the formula V = a³ where a is the length of a side. The mass of the cube is 15.4 g, and therefore the density can be calculated by dividing the mass by the volume.

To find the volume of the cube:
V = 1.2 cm × 1.2 cm × 1.2 cm = 1.728 cm³.

Now, to get the density:
density = mass/volume = 15.4 g / 1.728 cm³ ≈ 8.91 g/cm³. This density can be matched to a list of metallic element densities to identify the metal.

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To find the enthalpy change for the dissolution of sodium hydroxide, calculate the heat absorbed by the water (
H = -q / n), convert the mass of NaOH to moles, and divide the heat absorbed by the number of moles.

To calculate the enthalpy change (
H) for the solution process of sodium hydroxide (NaOH), we'll use the formula
H = -q / n, where 'q' is the heat absorbed by the water and 'n' is the number of moles of NaOH.

Step 1: Calculate the amount of heat absorbed (q) using the formula q = mc
delta T, where 'm' is the mass of the water plus the NaOH, 'c' is the specific heat capacity of water (4.18 J/g°C), and
delta T is the change in temperature.

Step 2: Convert the mass of NaOH to moles by using its molar mass (40.00 g/mol).

Step 3: Calculate
H using the moles and the heat absorbed.

For our case:

q = (100.0 g + 6.50 g)
4.18 J/g°C
(37.8°C - 21.6°C)

Calculate q and convert it to kilojoules, since 1 kJ = 1000 J.

6.50 g of NaOH is 0.1625 mol, because 6.50 g / 40.00 g/mol = 0.1625 mol.

Step 4: Now apply the formula
H = -q / n.

Final answer:

0.2495 moles of  [tex]O_2[/tex] are required for the complete combustion of 2.2 g of [tex]C_3H_8[/tex] to form [tex]CO_2[/tex] and [tex]H_2O[/tex]. This is calculated based on the balanced chemical equation for the combustion of propane and the molar mass of  [tex]C_3H_8[/tex].

Explanation:

To determine how many moles of [tex]O_2[/tex] are required for the complete combustion of 2.2 g of  [tex]C_3H_8[/tex] to form  [tex]CO_2[/tex] and H2O, we need to use the balanced chemical equation for the combustion of propane (C3H8):

[tex]C_3H_8[/tex] + 5 [tex]O_2[/tex] → 3 [tex]CO_2[/tex] + 4[tex]H_2O[/tex]

First, we calculate the moles of C3H8:

moles of C3H8 = mass (g) / molar mass (g/mol)

molar mass of  [tex]C_3H_8[/tex] = 44.10 g/mol

moles of  [tex]C_3H_8[/tex] = 2.2 g / 44.10 g/mol = 0.0499 mol

From the balanced equation, 1 mole of  [tex]C_3H_8[/tex] reacts with 5 moles of  [tex]O_2[/tex]. So, for 0.0499 moles of  [tex]C_3H_8[/tex], the moles of  [tex]O_2[/tex] required would be:

moles of  [tex]O_2[/tex] needed = 0.0499 mol  [tex]C_3H_8[/tex] × 5 moles O2/mol  [tex]C_3H_8[/tex] = 0.2495 mol  [tex]O_2[/tex]

0.2495 moles of  [tex]O_2[/tex] are required for the complete combustion of 2.2 g of  [tex]C_3H_8[/tex].

The answer is:

E per gram = 0.45 V

The explanation:

when MnO2 is the substance who oxidized here so, the oxidizing agent and the anode here is Li.

and when the molar mass of Li is = 7 g/mol

and in our reaction equation we have 1 mole of Li will give 3.15 V of the electrical energy

that means that :

7 g of Li gives → 3.15 V

So 1 g of Li will give→ ???

∴ The E per gram = 3.15 V / 7 g of Li

= 0.45 V

The correct answer is "The crystals did not phosphoresce within the drawer but did expose the film."

Becquerel  is credited to have discovered radioactivity. Becquerel was studying the properties of x-ray using naturally fluorescent minerals. Uranium shows radioactive decay. It is the high energy invisible radiation from uranium that exposed the photographic film.

Answer is: adding NaCl will lower the freezing point of a solution.

A solution (in this example solution of sodium chloride) freezes at a lower temperature than does the pure solvent (deionized water).

The higher the solute concentration (sodium chloride), freezing point depression of the solution will be greater.

Equation describing the change in freezing point:  

ΔT = Kf · b · i.

ΔT - temperature change from pure solvent to solution.

Kf - the molal freezing point depression constant.

b -  molality (moles of solute per kilogram of solvent).

i - Van’t Hoff Factor.

Dissociation of sodium chloride in water: NaCl(aq) →  Na⁺(aq) + Cl⁻(aq).

It lost electrons and was oxidized

Scientist can learn about Appearance of an organism and its structure by studying the fossils. hence, option" 2" Is correct.

By the method of radiocarbon-dating scientist can learn about an organism and its structures in the fossils, different kinds of rocks  and about the earth strata.

hence, option" 2" is the correct option.

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The total pressure in the container is approximately 3.00 atm

The question asks for the total pressure in a container holding different gases at a certain temperature, which is a typical problem in chemistry dealing with the ideal gas law. The ideal gas law is PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant (0.0821 atm·L/mol·K), and T is temperature in Kelvin.

To find the total pressure, we need to calculate the moles of each gas using their molar masses (He: 4.00 g/mol, F2: 38.00 g/mol, Ar: 39.95 g/mol), convert the temperature to Kelvin (18.0 °C + 273.15 = 291.15 K), and plug these values into the ideal gas law:

Using the ideal gas law:
P = (nRT) / V

P = (1.826 mol × 0.0821 atm·L/mol·K × 291.15 K) / 12.0 L

P ≈ 3.68 atm

Thus, the total pressure in the container is approximately 3.68 atm.

Answer: The correct statement is a hydronium ion donor in a reaction.

Explanation:

According to Arrhenius concept, a base is defined as a substance which donates hydroxide ions [tex](OH^-)[/tex] when dissolved in water and an acid is defined as a substance which donates hydronium ions [tex](H_3O^+)[/tex] in water.

According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

A substance that increases the hydroxide ion concentration of a solution is an Arrhenius base.

Hence, the correct statement is a hydronium ion donor in a reaction.

You can find the number of molecules in a given mass of substance by first finding the number of moles in the mass, and then multiplying by Avogadro's number. Using this method, 237 grams of CCl4 contains approximately 9.27 × 10^23 molecules.

To calculate the number of molecules in 237 grams of CCl4, you need to understand Avogadro's number and the concept of the mole. The molar mass of CCl4 is about 154 g/mol. So, first let's find out how many moles are in 237 grams.

Number of Moles = Mass / Molar Mass = 237 g / 154 g/mol = 1.54 moles.

Avogadro's number states there are 6.02214076 × 10^23 molecules in one mole.

So, the number of molecules in 1.54 moles would be: Number of Molecules = Number of Moles * Avogadro's Number = 1.54 moles * 6.02214076 × 10^23 molecules/mole

The result is approximately 9.27 × 10^23 molecules of CCl4.

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There are approximately 9.28  imes 10^23 molecules of CCl4.

To calculate the number of molecules in 237 grams of CCl4 (carbon tetrachloride), we first need to determine the molar mass of CCl4. The molar mass of carbon (C) is approximately 12.01 g/mol, and that of chlorine (Cl) is approximately 35.45 g/mol. Since CCl4 has one carbon atom and four chlorine atoms, its molar mass is (12.01 g/mol + (4  imes 35.45 g/mol) = 153.81 g/mol.

Next, we use the given mass of CCl4 to find the number of moles:

237 g CCl4  imes  rac{1 mol CCl4}{153.81 g CCl4} = 1.541 moles of CCl4

Using Avogadro's number, which is 6.022  imes 1023 molecules per mole, we can then calculate the number of molecules:

1.541 moles  imes 6.022  imes 1023 molecules/mol = 9.28  imes 1023 molecules of CCl4

So, there are approximately 9.28  imes 1023 molecules in 237 grams of CCl4.

               Volume =  19.6 L

                     As we know that one mole of any Ideal gas at standard temperature and pressure occupies exactly 22.4 dm³ volume.

Using this reference, we can calculate the volume occupied by Krypton (Ideal situation) as,

                     1 mole of Kr occupies  =  22.4 L of Volume

So,

                  0.875 moles of Kr will occupy  = X L of Volume

Solving for X,

                       X =  (0.875 mol × 22.4 L) ÷ 1 mol

                      X =  19.6 L

Answer:

For the tower to be the same distance from each of the centers, the company must find the point that is equidistant from the vertices of the triangle. This is the circumcenter of the triangle and can be found by constructing the point of concurrency of the perpendicular bisectors of the triangle.

Explanation:

sample response

Considering the chemical formula, there are 30 moles of O in 10 moles of KClO₃.

Chemical formulas use letters and numbers to represent chemical species, that is, compounds and ions.

The letters are called chemical symbols. They represent the elements present in the chemical species.

The numbers that accompany these letters are what we call subscripts.

A subscript is a number indicating the number of the element present in that compound. If no subscript appears after a chemical symbol, this implies that there is only one atom of that element.

In this case, the chemical formula KClO₃ indicates that 1 mole of the compound has:

So you can apply the following rule of three: if 1 mole of KClO₃ contains 3 moles of O, 10 moles of KClO₃ contains how many moles of O?

[tex]amount of moles of O=\frac{10 moles of KClO_{3} x3 moles of O}{1 moles of KClO_{3}}[/tex]

amount of moles of O= 30 moles

Finally, there are 30 moles of O in 10 moles of KClO₃.

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There are 30 moles of Oxygen in 10 moles of KClO3.

The chemical formula for potassium chlorate (KClO3) indicates that there is one oxygen atom for each molecule of KClO3. Therefore, the molar ratio of oxygen to potassium chlorate is 1:1. This means that for every mole of KClO3, there is one mole of oxygen atoms.

 Given that we have 10 moles of KClO3, we can directly apply the 1:1 molar ratio to find the number of moles of oxygen. Since there is no need for a conversion factor, the number of moles of oxygen is simply equal to the number of moles of KClO3.

Thus, 10 moles of KClO3 contains:

[tex]\[ 10 \text{ moles of KClO3} \times \frac{1 \text{ mole of O}}{1 \text{ mole of KClO3}} = 10 \text{ moles of O} \][/tex]

However, each molecule of KClO3 contains 3 oxygen atoms. Therefore, to find the total number of moles of oxygen atoms, we need to multiply the number of moles of KClO3 by the number of oxygen atoms per molecule:

[tex]\[ 10 \text{ moles of KClO3} \times \frac{3 \text{ moles of O}}{1 \text{ mole of KClO3}} = 30 \text{ moles of O} \][/tex]

So, there are 30 moles of oxygen atoms in 10 moles of KClO3.

To deposit 1.00 g of platinum with a current of 0.15 A, it will take approximately 1.831 hours. This is calculated by first determining the number of moles of Pt, then calculating the moles of electrons, converting them to coulombs using Faraday's constant, and finally using the charge to find the time required.

Calculating Time for Electrodeposition

To calculate the time it takes to deposit 1.00 g of platinum (Pt) using a current of 0.15 A in an electrolytic cell, we first need to determine the number of moles of Pt to be deposited. Using the molar mass of Pt (195.1 g/mol), we have:

Number of moles (Pt) = mass (Pt) / Molar mass (Pt)

= 1.00 g / 195.1 g/mol

= 0.005126 moles

Platinum (Pt) is deposited according to the reaction:

Pt2+ + 2e- → Pt(s)

Two moles of electrons are required to deposit one mole of Pt.

Number of moles of electrons = 2 × Number of moles (Pt)

= 2 × 0.005126

= 0.010252 moles

Next, we convert moles of electrons to coulombs using Faraday's constant, which states that 1 mole of electrons is equivalent to 96485 C:

Total charge (Q) = Number of moles of electrons × Faraday's constant

= 0.010252 moles × 96485 C/mol

= 989.2 C

Finally, we use the formula Q = It to find time (t), where I is the current and t is the time.

To find the time:

Time (t) = Total charge (Q) / Current (I)

= 989.2 C / 0.15 A

= 6594.67 seconds

To convert seconds to hours, divide by 3600:

Time in hours = 6594.67 s / 3600 s/h

= 1.831 hours

Answer:

Hydrogen bondings are shown below.

Explanation:

Hydrogen bonding takes place between an electronegative atom (O, N and F) and H atom attached to those electronegative atoms (O, N and F). Lone pairs on electronegative atoms are involved in formation of hydrogen bond.

Electronegative atom of a molecule which donates it's lone pair to form hydrogen bonding is called hydrogen bond donor. And the other molecule whose H atom is involved in hydrogen bonding is called hydrogen bond acceptor.

Hydrogen bond is a kind of bond whose strength is an intermediate to ionic and covalent bond.

Hydrogen bonding is represented as dash lines.

Hydrogen bonding between ammonia molecules and between ammonia and water molecule has been shown below.

Hydrogen bonding in ammonia molecules occurs due to attraction between the nitrogen atom of one molecule (negative charge) and the hydrogen atom of another (positive charge). The same principle applies between an ammonia molecule and a water molecule.

Hydrogen bonding in ammonia molecules (NH3) occurs due to attraction between the nitrogen atom of one molecule, which carries a partial negative charge, and the hydrogen atom of another molecule which carries a partial positive charge. With regard to an ammonia molecule and a water molecule (H2O), hydrogen bonds can form in a similar fashion.

The partial positively charged hydrogen atom of the ammonia molecule can attract the partial negatively charged oxygen atom of the water molecule, forming a bond.

Similarly, the partial positively charged hydrogen atoms of the water molecule can attract to the partial negatively charged nitrogen atom of ammonia, creating another hydrogen bonding.

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The density of the substance is denoted by the symbol ρ or D. The mass of the ethanol sample with a density of 0.789 g/ml in 150 mL at 20°C will be 118.35 g.

The density of the object has been defined by the mass divided by the unit of volume and shows the direct relationship between mass and density. A heavier object has more density as compared to a lighter object.

The formula for density is given as,

Density = mass ÷ volume

or Mass = density × volume

Given,

Density = 0.789 gm/mL

Volume = 150 mL

Mass is calculated by substituting values in the above formula as,

Mass = density × volume

Mass = 0.789 gm/mL × 150 mL

Mass = 118.35 g

Therefore, a 150.0 mL ethanol at a temperature 20°C with a density of 0.789 gm/mL has a mass of 118.35 g.

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Final answer:

A neutral atom must have the same number of electrons and protons.

Explanation:

A neutral atom must have the same number of electrons and protons. Therefore, if an atom has 3 electrons outside of its nucleus, it must also have 3 protons in its nucleus to be neutral. The number of neutrons does not affect the overall charge of the atom.

For example, a lithium atom (Li) has an atomic number of 3, which means it has 3 protons. If it also has 3 electrons, it will have a net charge of zero and be neutral.

In general, if an atom has a certain number of electrons, it must have an equal number of protons to maintain neutrality.