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Monel metal is a corrosion-resistant copper-nickel alloy used in the electronics industry. A particular alloy with a density of 8.80 g/cm3 and containing 0.073% Si by mass is used to make a rectangular plate that is 15.0 cm long, 12.5 cm wide, and 2.50mm thick and has a 2.50-cm-diameter hole drilled through its center such that the height of the hole is 2.50mm . The silicon in the plate is a mixture of naturally occurring isotopes. One of the those isotopes is silicon-30, which has an atomic mass of 29.97376 amu and a percent natural abundance of 3.10% How many silicon-30 atoms are found in this plate? Express your answer numerically using two significant figures.


Answer is: there are 1.82·10²⁰ silicon-30 atoms.

V₁(alloy) = 15 cm · 12.5 cm · 0.25 cm.

V₁(alloy) = 46.875 cm³; volume of the alloy without hole.

V(hole) = 0.25 cm · (1.25 cm)² · 3.14.

V(hole) = 1.23 cm³

V₂(alloy) = 46.875 cm³ - 1.23 cm³.

V₂(alloy) = 45.65 cm³; volume of the alloy with hole.

m(alloy) = V₂(alloy) · d(alloy).

m(alloy) = 45.65 cm³ · 8.80 g/cm³.

m(alloy) = 401.7 g; mass of the alloy.

ω(Si) = 0.073% ÷ 100%.

ω(Si) = 0.00073.

m(Si) = ω(Si) · m(alloy).

m(Si) = 0.00073 · 401.7 g.

m(Si) = 0.293 g; mass of silicon it the alloy.

m(Si-30) = m(Si) · ω(Si-30).

m(Si-30) = 0.293 g · 0.031.

m(Si-30) = 0.0091 g; mass of the silicon-30.

n(Si-30) = m(Si-30) ÷ M(Si-30).

n(Si-30) = 0.0091 g ÷ 29.97376 g/mol.

n(Si-30) = 0.000303 mol; amount of the silicon-30.

N(Si-30) = n(Si-30) · Na (Avogadro constant).

N(Si-30) = 0.000303 mol · 6.022·10²³ 1/mol.

N(Si-30) = 1.824·10²⁰.


Related Questions

Posted in Chemistry

Indicate whether the following are acidic, basic, or neutral solution A. [H2O+]=6.0x10^-12 B. [H3O+]=1.4x10^-9 C. [OH-]=5.0x10^-12 D. {OH-]=3.5x10^-10

You answer this by using the pH formula and and the relation of pH and pOH, pH = -log[H+] and 14 = pH + pOH. The correct classification are as follows:

A. [H2O+]=6.0x10^-12
basic

B. [H3O+]=1.4x10^-9
basic

C. [OH-]=5.0x10^-12
acidic

D. {OH-]=3.5x10^-10
acidic

Hope this answers the question.

Posted in Chemistry

Which statement best explains why a carbon atom can bond easily with other atoms? It is an ion. It is an organic element. It has four valence electrons. It forms hydrogen bonds.

Based on the definition of a carbon atom, the statement that best explains why a carbon atom can bond easily with other atoms because it  has four valence electrons. So the answer would be the third option. Hope this answers your question.

Posted in Chemistry

Sulfur and fluorine react in a combination reaction to produce sulfur hexafluoride: S(g) + 3F2(g) ->SF6(g) If 50 g S is allowed to react as completely as possible with 105.0g F2(g), what mass of the excess reactant is left.

The balanced chemical reaction is:

S(g) + 3F2(g) ->SF6(g)

We are given the amount of the reactants to be used in the reaction. We use these as the starting values for the calculations. We calculate as follows:

50 g S ( 1 mol / 32.066 g ) = 1.56 mol S
105 g F2 ( 1 mol / 38.00 g ) = 2.76 mol F2

The limiting reactant would be F2 since it will be consumed completely in the reaction. The excess reactant would be S. 

Mass of excess = 1.56 mol - 2.76(1/3) = 0.64 mol S excess

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Posted in Chemistry

In the following reaction, how many grams of oxygen will react with 10.47 grams of benzene (C6H6)? 2C6H6 + 15O2 12CO2 + 6H2O The molar mass of benzene is 78.1074 grams and that of O2 is 32 grams.

The balanced chemical reaction is:

2C6H6 + 15O2 = 12CO2 + 6H2O

We are given the amount of benzene to be used in the reaction. We use this as the starting point for the calculations. We do as follows:

10.47 g C6H6 ( 1 mol / 78.1074 ) ( 15 mol O2 / 2 mol C6H6 ) ( 32 g / mol ) = 32.17 g O2

Posted in Chemistry

You carefully weigh out 14.00 g of CaCO3 powder and add it to 56.70 g of HCl solution. You notice bubbles as a reaction takes place. You then weigh the resulting solution and find that it has a mass of 64.96 g . The relevant equation is CaCO3(s)+2HCl(aq)→H2O(l)+CO2(g)+CaCl2(aq) Assuming no other reactions take place, what mass of CO2 was produced in this reaction?

Answer : The mass of CO_2 produced will be, 6.16 grams.

Explanation : Given,

Mass of CaCO_3 = 14 g

Mass of HCl = 56.70 g

Molar mass of CaCO_3 = 100 g/mole

Molar mass of HCl = 36.5 g/mole

Molar mass of CO_2 = 44 g/mole

First we have to calculate the moles of CaCO_3 and HCl.

\text{Moles of }CaCO_3=\frac{\text{Mass of }CaCO_3}{\text{Molar mass of }CaCO_3}=\frac{14g}{100g/mole}=0.14moles

\text{Moles of }HCl=\frac{\text{Mass of }HCl}{\text{Molar mass of }HCl}=\frac{56.70g}{36.5g/mole}=1.55moles

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

CaCO_3(s)+2HCl(aq)\rightarrow CO_2(g)+H_2O(l)+CaCl_2(aq)

From the balanced reaction we conclude that

As, 1 moles of CaCO_3 react with 2 mole of HCl

So, 0.14 moles of CaCO_3 react with 0.14\times 2=0.28 moles of HCl

From this we conclude that, HCl is an excess reagent because the given moles are greater than the required moles and CaCO_3 is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of CO_2.

As, 1 moles of CaCO_3 react to give 1 moles of CO_2

So, 0.14 moles of CaCO_3 react to give 0.14 moles of CO_2

Now we have to calculate the mass of CO_2.

\text{Mass of }CO_2=\text{Moles of }CO_2\times \text{Molar mass of }CO_2

\text{Mass of }CO_2=(0.14mole)\times (44g/mole)=6.16g

Therefore, the mass of CO_2 produced will be, 6.16 grams.

Posted in Chemistry

A compound contains 69.94 percent iron and 30.06 percent oxygen. What is its molecular formula if the molar mass of the compound is 199.55 grams per mole?

Answer:

The molecular formula is Fe₂O₃

Explanation:

The molar mass of the compound is 199.55 g/mol; this means that if we have 1 mol of the compound, we'd have 199.55 g, we'd also have:

  • 199.55 * 69.96/100 = 139.57 g of iron
  • 199.55 * 30.06/100 = 59.98 g of oxygen

Now we calculate the moles of each element present in the given masses, using their atomic masses:

  • 139.57 g Fe ÷ 55.84 g/mol = 2.50 mol Fe
  • 59.98 g O ÷ 16 g/mol = 3.75 mol O

Then in 1 mol of the compound, there's 2.50 mol Fe and 3.75 mol O:

  • Fe₂.₅O₃.₇₅

We convert the coefficients into integers (Divide them by the lowest number among them and multiply them by two):

  • Fe₂O₃

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Posted in Chemistry

Which of the following are most likely to form a metallic bond? several gold atoms copper and chlorine magnesium and chlorine several chlorine atoms

I think the correct answer from the choices listed above is the first option. It would be several gold atoms that will form a metallic bond. It is the most logical choice since it is a metal while the others are nonmetal and a combination of metal and nonmetal. Hope this answers the question. Have a nice day.

Posted in Chemistry

One of the isotopes of sulfur is represented as sulfur-35 or S-35. What does the number 35 signify?

One of the isotopes of sulfur is represented as sulfur-35 or S-35. The number 35 represents the mass number of the isotope. The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus.

Posted in Chemistry

Which of the following is a possible set of quantum numbers for an electron n, l, m subscript l, m subscript ? (1, 0, 0, +1) (2, 2, 1, +½) (4, -3, 0, -½) (3, 2, 1, -½)

So based on the given sets of quantum numbers above for an electron n,l,m subscript l, m subscript, the correct answer for this would be the last option. So the possible set of quantum numbers for an electron n, l, m subscript l, m subscript would be this: (3, 2, 1, -½). Hope this answers the question. 

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A chemist has 2.0 mol of methanol (CH₃OH). The molar mass of methanol is 32.0 g/mol. What is the mass, in grams, of the sample? 16 30 32 64

Answer:

64

Explanation:

Mole of a compound = mass of a compound / molar mass of a compound

Mass of a compound = mole of a compound x molar mass of a compound

Given,

Mole of methanol = 2 mol

Molar mass of methanol = 32 g/mol

Mass of methanol = Mole of methanol x Molar mass of methanol  

                               = 2 mol x 32 g/mol = 64 g

Therefore, the mass, in grams, of the sample = 64

Posted in Chemistry

A teacher makes the following statement. “Gasoline boils at a relatively low temperature (about 150°C). The kerosene is removed at around 200°C, followed by diesel oil at 300°C and fuel oil at around 370°C.” What topic is the teacher most likely talking about? a. distillation of a mixture b. filtration of a pure substance c.evaporation of a mixture d. sorting of a pure substance

Answer:

The correct answer is option a.

Explanation:

According the question, boiling points of different liquids are discussed which means that if we take all these liquids in single mixture we can separate them from each other on the basis of their difference in boiling point. And the technique which employs this principle is distillation process.

Hence, we can say teacher is most likely talking about distillation of a mixture of oils.

Distillation is a process which is used to separate mixture of different liquids from each other. In this process, during the course of boiling of mixture liquid compound with lower boiling points vaporizes first leaving behind the liquid with higher boiling point behind.

And vapors of boiled liquid are condensed down in a separate container for the collection.

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Posted in Chemistry

Choose one property of water that makes it unique describe the property and explain the chemical or physical reasons that causes water to have to property.

Water has high heat specific capacity. Heat specific capacity is the amount of heat that is needed to raise the temperature of one gram of particular substance by one degree Celsius. The high specific heat capacity of water is due to the hydrogen bond that exist among the molecules of water. The hydrogen bond is quite strong and it will take a lot of heat to break the bonds. Thus, it takes a lot of heating to increased the temperature of water by one degree Celsius. This is also the reason why water has high boiling point.

Posted in Chemistry

What is the mass of 5.05×1021 platinum atoms?

Answer: 1.6 gram

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 6.023\times 10^{23} of particles.

To calculate the moles, we use the equation:

\text{Number of moles}=\frac{\text{Given atoms}}{\text {Avogadro's Number}}

\text{Number of moles of water}=\frac{5.05\times 10^{21}}{6.023\times 10^{23}}=8.4\times 10^{-3}moles

1 mole of Platinum Pt weighs 195 g

8.4\times 10^{-3}moles  of Platinum Pt weigh =\frac{195}{1}\times 8.4\times 10^{-3}=1.6g

Thus mass of 5.05\times 10^{21} platinum atoms is 1.6 gram.

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Posted in Chemistry

Which statement best characterizes chemical reactions? They always occur very quickly. Their rates vary significantly. Their rates are always slow. They rarely occur in the natural environment.

I think the correct answer from the choices listed above is the second option. The statement that best characterizes chemical reactions would be that their rates vary significantly. Each reaction has its own rate and it depends on the conditions the reactants are subjected to. Hope this answers the question.

Posted in Chemistry

Which of these is a property of a substance that is composed of atoms that are held together by ionic bonds? It can be shaped into wires. It has a low melting point. It conducts electricity when in solid form. It conducts electricity when it is dissolved in water.

Answer: Option (D) is the correct answer.

Explanation:

A ionic compound will have opposite charges on the 2 atoms attached to each other.

When ionic compound is in solid state then atoms will be more closer to each other and also due to the opposite charges the molecules will have strong force of attraction between them.

In order to conduct electricity, free movement of ions is required. So, a solid with ionic bonds is not able to conduct electricity as molecules or ions are closely held together.

Whereas when a substance that is composed of atoms that are held together by ionic bonds is dissolved in water then its ions will start to move freely from one point to another. Thus, this solution will be able to conduct electricity.

Thus, we can conclude that out of the given options, conducts electricity when it is dissolved in water displays a property of a substance that is composed of atoms that are held together by ionic bonds.

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Posted in Chemistry

What does newtons third law say about why momentum is conserved in collisions?

Newton's third law of motion is naturally applied to collisions between two objects. In a collision between two objects, both objects experience forces that are equal in magnitude and opposite in direction.For such a collision, the forces acting between the two objects are equal in magnitude and opposite in direction

Posted in Chemistry

What is the mass number of 80Br

Mass number of an element write in bottom of it!

So, there 80 would be the mass number of ₈₀Br.

Hope this helps!

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Which of the following statements about the use of nuclear energy is true? a. Nuclear energy cannot be used safely. b. Nuclear fusion has no known useful applications. c. Nuclear fission is currently more useful for producing energy than nuclear fusion. d. Nuclear fusion has fewer safety risks than nuclear fission.

Answer: The correct answer is "Nuclear energy cannot be used safely".

Explanation:

There are two types of nuclear reactions: Nuclear fission and Nuclear fusion.

Nuclear fission: The nuclear energy is originated from the splitting of uranium atom. Uranium is a radioactive material.

Nuclear reactor controls the release of energy.

The by product of the nuclear generation is the radioactive waste in the nuclear power plant.

The radioactive material emits harmful radiation. If there is any leakage in the power plant. Then, it would lead to hazard. It would harmful for the health of the employees who are working there.

Therefore, the correct option is (a).

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Carbon-14 has a half-life of 5730 years. In a plant fossil, you find that the 14C has decayed to 1/4.00 of the original amount. How long ago was this plant alive?

Answer:

The plant was alive for 1155 years

Explanation:

Any radioactive decay process follows the exponential law which is mathematically expressed as:

N(t)= N(0)e^{-kt}------(1)

where N(0) = initial amount of the radioactive material

N(t) = amount at time t

k = decay constant

The decay constant is in turn related to the half-life t1/2

k = \frac{0.693}{t1/2}----(2)

It is given that t1/2 of 14C = 5730yrs. Therefore:

k = \frac{0.693}{5730}=1.21*10^{-4}yr-1

In addition it is mentioned that:

N(t) = 1/4*N(0)

substituting this in equation (1) gives:

1/4*N(0)= N(0)e^{-1.21*10^{-4}t}

t = 1155 years

Posted in Chemistry

How can you tell if an object has elastic properties? A.)If two people pulls on it in opposite directions it falls apart B)If two people pull on it ,it maintains its original size and shape C)if two people pull on it in opposite directions ,it stretches and remains in a new shape D.)if two people pull on it in opposite direction,it stretches.Then when they let it go, it turns to its original size and shape

13.2 Elasticity Elasticity is a fundamental property of materials. Springs of all kinds are examples of elastic bodies. Let us consider the characteristics of a spring. We find that a spring will respond to distorting force and then return to its original shape after the distorting force is removed. Any material or body can be deformed by an applied force. If it returns to its original shape after the force is removed, it is said to be elastic. Most substances are elastic to some degree. In a technical sense a substance with a high elasticity is one that requires a large force to produce a distortion-for example, a steel sphere!

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Posted in Chemistry

Calculate the mass in atomic mass units of 0.25 mol of carbon-12 atoms

Carbon has a mass of 12.01amu/mol
12.01/4=3.025
3.025 grams/amu

Posted in Chemistry

Which subatomic particle contains the energy stored in chemical bonds

Pretty sure that the energy stored in chemical bonds is ATP, so probably the mitochondria? idk if thats what you are asking

Posted in Chemistry

How many oxygen atoms in 1 mole of CO2

So one mole is 6.022*10^34 molecules/atoms I think so then multiple that by two bc u have two oOs per c u have 12.044*10^34 atoms

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