Describe how the suspects used the chemicals found at the crime scene to make the copper coins look silver.

Answers

Answer 1

The chemicals found at the crime scene although not mentioned must be Sodium zincate.

Discussion:

An interesting demonstration to show plating and alloys is the conversion of copper coins to silver look-alike coins.

A 'copper' coin when dipped into a solution of sodium zincate in contact with zinc. The coin is plated with zinc and appears silver in colour.

This is a common chemistry classroom trick.

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Related Questions

How many molecules are in 25.3g of C2H4O

Answers

Answer:

0.57 molecules

Explanation:

What type of molecule is pentanal?
A. Aldehyde
O B. Ketone
O C. Alcohol
O D. Ester

Answers

Answer:

[tex] \huge \color{indigo} \boxed{a. \: aldehyde}[/tex]

Explanation:

Pentanal is considered to be a fatty aldehyde lipid molecule. These are compounds containing more than one aldehyde group. Pentanal is a very hydrophobic molecule, practically insoluble in water, and relatively neutral.

what word describes when tiny droplets of one liquid are finely dispersed within another liquid?

Answers

When tiny droplets of one liquid are finely dispersed within another liquid it is called emulsion.

Emulsion can be defined as the process by which two liquids that are not miscible come together to form a mixture.

The emulsion mixture usually consists of an oil phase and a water phase.

The oil phase appears as droplets when dispersed (mixed with) the water phase.

The uses of emulsion include:

It is used in chemical industries for production.

It is used for production of medicine.

Digestion of fatty food components in the intestine takes place through the process of emulsion.

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mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron. carbon. plastic. glass.

Answers

Iron because iron is the only one magnetic of the three

Mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.

What is iron?

The chemical element iron has the atomic number 26 and the symbol Fe. It is a metal that is found in group 8 of a periodic table and the first transition series. It makes up a large portion of the planet's outer or inner core and is the most prevalent element on Earth by mass, just ahead of oxygen.

It is the fourth most prevalent element in the crust of the Earth, having been mostly deposited by meteorites inside its metallic state, along with its ores. Iron ores must be processed in kilns or furnaces that may reach 5000 °C (2,730 °F) and higher, which is approximately 500 °C (932 °F) greater than the temperature needed to smelt copper. Mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.

Therefore, mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.

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Will the things dissolve by themselves over time?​

Answers

When a substance dissolves, it looks like it disappears. But in fact it has just mixed with the water to make a transparent (see-through) liquid called a solution. A solution has two parts. The solute is the solid that gets dissolved.

Answer:

it really depends what they are

Explanation:

What is carbon? What does it do?

Answers

The Short Answer: Carbon is in carbon dioxide, which is a greenhouse gas that works to trap heat close to Earth. It helps Earth hold the energy it receives from the Sun so it doesn't all escape back into space. If it weren't for carbon dioxide, Earth's ocean would be frozen solid.

Add 2 teaspoons of baking soda and 2 teaspoons of citric acid to the foam cup. Add the half cup of water to the cup and stir. What is the temperature?

Answers

Answer:

Test for carbon dioxide gas.

The reaction between baking soda and citric acid will form sodium ions, citric acid ions, carbon dioxide gas, and water. So all you have to do is add the gas produced (by gas displacement method or something) and test whether the gas is carbon dioxide, with lime water or other methods like hydrogencarbonate indicator. Hope this helped!

Explanation:

Answer:

depends on amount, but the reaction's endothermic (meaning its cold, absorbs heat from surroundings)

I hope it helps.

The burning of fossil fuels contributes to the addition of greenhouse gases to the atmosphere. These gases trap thermal energy in the Earth’s atmosphere. Which of the following would be the most reasonable changes that could result from an increase in the burning of fossil fuels?

Answers

Explanation:

The burning of fossil fuels contributes to the addition of greenhouse gases to the atmosphere. These gases trap thermal energy in the Earth's atmosphere.

The materials which contain hydrocarbons which are generated from the remains of decay of plants and animals that are buried underground for many years are called fossil fuels.

What causes by burning fossil fuels?

The burning of fossil fuels can affect the environment, climatic conditions and human health. The burning of fossil fuels produces large amount of green house gases like CO₂, CH₄, etc. The increase in the amount of green house gases increases the heat and temperature of the earth's surface which leads to global warming.

The increase of temperature due to global warming can cause rise in the sea level, the glaciers of the earth will melt and coastal areas will be submerged under water due to this.

The burning of fossil fuels also releases toxic gases like SO₂, NO₂ which can cause acid rain and the emission these gases causes air pollution.

Thus the burning of fossil fuels has adverse effects.

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I NEED THE ANSWER ASAP! Its science btw

Which statement describes conditions in which a mineral can form?
A. Crystals of minerals dissolve in the groundwater in caves.

B. Materials dissolved in seawater crystallize on an ocean bottom.

C. Molten materials are cooled in a netalworks factory

D. Materials are mined from deposits deep underground.​

Answers

A. Crystals of minerals dissolve in the groundwater in caves

Answer:

b

Explanation:

Solid calcium hydroxide is dissolved in water until the pH of the solution is 11.44. The hydroxide ion concentration [OH–] of the solution is:______.A. 1.1 * 10-11 M.B. 3.06 M.C. 8.7 * 10-4 M.D. 1.0 * 10-14 M.E. None of these.

Answers

Answer:

c the answer is c that is the answer

Draw the structure of the product that is formed when the compound shown below undergoes a reaction with 1 equivalent of ch3mgi and then is treated with water.

Answers

When the compound shown is treated CH3MgI followed by water, 1,3 - cyclohexadienol is formed.

Grignard reagent is an alkylmagnesium halide. Grignard reagents are important synthetic tools in chemistry. They are used to synthesize and number of compounds in the laboratory.

When the Grignard reagent, CH3MgI is reacted with compound shown followed by treatment with water, the product of the reaction is 1,3 - cyclohexadienol whose structure is shown in the second image attached to this answer.

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How are mitosis and meiosis similar? How are they different? Provide 1 way the two processes are the same and 2 ways the 2 processes are different.

Answers

Answer:

Similar: both processes of cell division; both processes take place in the nucleus of the cell

Different: mitosis divides into 2, meiosis divides into 4; one is the division of body cells and the other is of specifically sex cells

Explanation:

https://byjus.com/biology/mitosis-and-meiosis/

^ this has more info!

22) Calculate the energy of a photon of radiation with a frequency of 9.50 x 1013 Hz.

Answers

The energy of the photon with a frequency of 9.50×10¹³ Hz is 6.29×10¯²⁰ J

From the question given above, the following data were obtained:

Frequency (f) = 9.50×10¹³ Hz

Planck's constant (h) = 6.626×10¯³⁴ Js

Energy (E) =?

The energy of the photon can be obtained as follow:

E = hf

E = 6.626×10¯³⁴ × 9.50×10¹³

E = 6.29×10¯²⁰ J

Therefore, the energy of the photon is 6.29×10¯²⁰ J

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What is the agent that causes frost wedging?

Answers

Answer:

Freeze wedging is caused by the repeated freeze-thaw. Frost wedging occurs as the result of 9% expansion of water when it is converted to ice. Cracks filled with water are forced further apart when it freezes.

Infrared waves travel at a speed of 3.00 x 10^8 m/s. What is the frequency of an infrared wave
that has a vacuum wavelength of 5.5 micrometers?
(1 micrometer= 1x10^-6 m)
O 5.5 X 10^12 Hz
O 5.5 x 10^10 Hz
O 5.5 X 10^11 Hz
O 5.5 X 10^13 Hz

Answers

The frequency of the infrared wave at the given speed and wavelength is [tex]5.5 \times 10^{13} \ Hz[/tex].

The given parameters;

speed of the wave, v = 3 x 10⁸ m/swavelength of the wave, λ = 5.5 μm

The frequency of the infrared wave is calculated by using wave equation as shown below;

v = fλ

where;

f is the frequency of the wave

[tex]f = \frac{v}{\lambda} \\\\f = \frac{3\times 10^8}{5.5 \times 10^{-6}} \\\\f = 5.5 \times 10^{13} \ Hz[/tex]

Thus, the frequency of the infrared wave at the given speed and wavelength is [tex]5.5 \times 10^{13} \ Hz[/tex].

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what is the periodic trend for electronegativity

Answers

Answer:

mark me brainlest

Explanation:

Electronegativity values generally increase from left to right across the periodic table. Electronegativities generally decrease from top to bottom of a group. The highest electronegativity value is for fluorine.

Answer:

       "Electronegativity increases as you move from left to right across a period because the number of charges on the nucleus increases." (sstudy30 on Quizlet)

Explanation:

    It explains itself haha!

Have a nice day!

    I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)

- Heather

Compared to the energy of an electron in the second shell of an atom of sulfur, the energy of an electron in the
1
first shell is lower
2
first shell is the same.
3
third shell is lower
4
third shell is the same.

Answers

Answer:

First shell is lower

Explanation:

The electron has to absorb energy to excite and go to higher energy levels/ shells and should release energy to go to lower energy levels/ shells. This means higher the shell , more energy is required and vice versa

You have a sealed 2 liter flask that contains nothing but water and carbon dioxide. The flask is half-filled with liquid water, has a temperature of 25°c, and the overall pressure within the flask is 0. 1 atm. How many moles of co2 are in the flask? at this temperature, you may take the kh value for co2 as 0. 033 m / atm.

Answers

In this exercise we want to calculate the amount of moles, so this is going to be:

[tex](4.6)(10^{-3}) \ mols \ CO_2[/tex]

Knowing that Henry's law is given by:

[tex]C = KHP[/tex]

Where constants are given by:

C = Concentration  KH = Henry's law constant = [tex]0.033 m/atm[/tex]P = partial pressure = [tex]0.07 atm[/tex]

Before we can find the concentration of CO2 (and hence the moles of CO2), we first need to find its partial pressure.  We look up the vapor pressure of water at 25º and find it to be 0.03 atm.  Since the total pressure is equal to 0.1 atm, this mean the partial pressure of:

 

[tex]CO_2 = 0.1 \ atm - 0.03 \ atm = 0.07 \ atm[/tex]

Now using Henry's law, we find the concentration:

[tex]C = (0.033)*( 0.07) = (2.31)*(10^{-3})[/tex]

Converting to moles of CO2, we have:

[tex](2.31)*(10^{-3})*( 2) = (4.6)*(10^{-3})[/tex]

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An unknown element sample has 2 isotopes present. The first isotope has a mass of 6.017 amu and is
7.30% abundant. The second has a mass of 7.018 amu and an abundance of 92.7%. Calculate the
average atomic mass of this element

Answers

Answer:

Calculating Atomic Mass

Change each percent abundance into decimal form by dividing by 100. Multiply this value by the atomic mass of that isotope. Add together for each isotope to get the average atomic mass.

Explanation:

have a nice day

methane is called an organic compound why​

Answers

Answer:

Explanation:

1) Organic compounds always contain only p-block elements (Groups III-VII), at least one of which must be carbon. 2) Organic compounds almost always contain one or more C-H bonds. ... Thus, all bonds are typically covalent in organic compounds. Methane (CH4) is the prototypical organic molecule.

Methane contains carbon, forming covalent bonds, and is found in living organisms, making it an organic compound.

Methane (CH₄) is considered an organic compound due to its molecular structure and occurrence in living organisms. Organic compounds are primarily composed of carbon atoms covalently bonded to hydrogen and often other elements like oxygen, nitrogen, sulfur, and more.

Methane consists of one carbon atom bonded to four hydrogen atoms through covalent bonds. Carbon's unique ability to form stable covalent bonds with other elements, including itself, leads to the vast diversity of organic molecules found in living organisms.

Methane is a crucial component of natural gas and is produced by various biological and geological processes. It is present in the digestive systems of animals, formed during decomposition, and plays a role in carbon and energy cycles.

Its prevalence in living systems and its molecular structure classify methane as an organic compound, reflecting the foundational principles of organic chemistry.

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The complete question is :

Methane is called an organic compound why​?

Explain how magnesium is produced at the negative electrode from molten magnesium chloride

Answers

Answer:

being cation it migerates to cathode to be reduced to elemental magnesium

Explanation:

Mg+2. +2e -----------Mg

How can you improve your ability to see the indicator color change at the endpoint of a titration?.

Answers

Answer: Place a piece of white paper under the analyte flask throughout the titration

Explanation:

The end point of titration can be made easy by the use of indicators. But we have to be keenly observe for each drop from the burette because, the colour change will be sudden for a drop.

What is titration?

Titration is an analytical technique used to determine the unknown concentration using a standard reagent of known concentration. The standard reagent of known concentration is called titrant and the  one to be determined is called analyte.

Usually analyte is taken in a conical flask and titrant in a burette. The end point of titration is the point at which the reaction is completed in perfect stoichiometry.

In acid-base titrations, the indicators used having different colors in different pH. Hence, the indicator in the analyte will change in color when the acidity of the medium changes. We have to observe keenly for the color change because it happens for any drop.

The adding of titrant from the burette must be dropwise and thus we can get a time to notice the sudden colour change of indicator.

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¿Qué relación existe entre la teoría del octeto de Lewis con los enlaces iónicos y
covalentes?

Answers

Por definición de enlace iónico, covalente y regla del octeto, la relación existente entre la teoría del octeto de Lewis con los enlaces iónicos y  covalentes es que dichos enlaces se producen con el objetivo de completar la última capa de electrones y adquirir estabilidad.

Enlace iónico

Por un lado, se produce un enlace iónico entre átomos metálicos y no metálicos, donde los electrones se transfieren completamente de un átomo a otro. Durante este proceso, un átomo pierde electrones y otro los gana, formando iones. Por lo general, el metal cede sus electrones formando un catión al elemento no metálico, que forma un anión.

Enlace covalente

Por otro lado, el enlace covalente es el enlace químico entre átomos donde los electrones se comparten, formando una molécula. Se establecen enlaces covalentes entre elementos no metálicos. El par de electrones compartidos es común a los dos átomos y los mantiene unidos.

Regla del octeto

En ambos casos se cumple con la regla del octeto, que establece que los átomos de los elementos se enlazan unos a otros en el intento de completar su capa de valencia con ocho electrones. Es decir que los átomos van a tender a ceder o compartir electrones para completar ocho electrones en la capa de valencia mediante un enlace iónico, covalente o metálico.

En otras palabras, el objetivo es tener la configuración electrónica del gas noble más cercano, teniendo así la última capa de electrones completa y adquiriendo estabilidad.

En resumen

En resumen, la relación existente entre la teoría del octeto de Lewis con los enlaces iónicos y  covalentes es que dichos enlaces se producen con el objetivo de completar la última capa de electrones y adquirir estabilidad.

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the proton concentrations of three solutions at 25 °c are given. classify the solutions as acidic, basic, or neutral.

Answers

This problem is giving information about the proton concentrations of three solutions at 25 °C. Despite they are not numerically given, we can propose three scenarios to see how to approach the question.

Let the following solutions to come up:

[H⁺] = 2.63x10⁻³ M

[H⁺] = 1.00x10⁻⁷ M

[H⁺] = 4.511x10⁻⁹ M

The first step, will be the calculation of the pH for each solution via:

pH = -log([H⁺])

So that they turn out to be:

pH = -log(2.63x10⁻³ M) = 2.580

pH = -log(1.00x10⁻⁷ M) = 7.000

pH = -log(4.511x10⁻⁹ M) = 8.3457

In such a way, since acidic solutions have a pH below 7, neutral have a pH equal to 7 and basic have it above 7, we infer the first one is acidic, second one is neutral and third one is basic.

Thus, you can reproduce this methodology with the proton concentrations you are given.

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a
A sample of gas has a volume of 3.50 L and a pressure of
125 mm Hg. What will the new pressure be when the volume
is decreased to 2.75 L? The temperature stays the same.

Answers

Answer:

159.09 mmHg

Explanation:

The new pressure can be found by using the formula for Boyle's law which is

[tex]P_2 = \frac{P_1V_1}{V_2} \\[/tex]

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

From the question we have

[tex]P_2 = \frac{125\times3.50 }{2.75} = \frac{437.5}{2.75} \\ = 159.090909...[/tex]

We have the final answer as

159.09 mmHg

Hope this helps you

DO the postulates of daltons atomic theory explain the law of consrevetion of mass and thelaw of constant composition

Answers

Answer:

see answer

Explanation:

DO the postulates of Daltons atomic theory explain the law of conservation of mass and the law of constant composition.

Dalton's Atomic Theory Postulates

1. Everything is composed of atoms, which are the indivisible building blocks of matter and cannot be destroyed or divided any further.

2. All atoms of a single pure element are the same in size and mass

3. Atoms of different elements vary from each other in size and mass.

4. Compounds are produced through different simple whole-number combinations of atoms to produce molecules.  

5. Anywhere a compound exists, it will have the same atoms in the same ratio.

6. A chemical reaction between compounds is a re-arrangement of atoms

The law of conservation of mass is shown in 2, 4. and 5.

The law of constant co,position is shown in 2, 4, 5, and 6

which characteristic do valence electrons indicate about reactions between atoms?

Answers

Bond number

The characteristic of reactions that depends on valence electrons is the bond type.

In chemistry, a chemical bond could be;

Ionic

Covalent

The type of bond formed depends on the number of valence electrons present. When there are few valence electrons on an atom, it mostly forms ionic bonds.

When there are more electrons on an atoms, it mostly forms covalent bonds and the electrons between the atoms are shared.

What mass of water absorbs 6700 J of heat to raise the temperature from 283K to 318K?​

Answers

Answer:

you did not give the specific heat like formula like it takes 1kj to raise 28grams of water by 10 grams

why does helium fusion require higher temperatures

Answers

Answer:

Nuclear fusion of hydrogen to form helium occurs naturally in the sun and other stars. It takes place only at extremely high temperatures. That's because a great deal of energy is needed to overcome the force of repulsion between the positively charged nuclei.

Explanation:

hope it helps

what is the difference in chemical energy between organic and inorganic materials?

Answers

Answer:

the difference is  the presence of a carbon atom

Explanation:

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