To 100.0 g water at 25.00 ºc in a well-insulated container is added a block of aluminum initially at 100.0 ºc. the temperature of the water once the system reaches thermal equilibrium is 28.00 ºc. what is the mass of the aluminum block? (the specific heat capacity of al is 0.900 j g–1 k–1 .)

Answers

Answer 1
when the amount of heat gained = the amount of heat loss

so, M*C*ΔTloses = M*C* ΔT gained

when here the water is gained heat as the Ti = 25°C and Tf= 28°C so it gains more heat.

∴( M * C * ΔT )W = (M*C*ΔT) Al

when Mw is the mass of water = 100 g 

and C the specific heat capacity of water = 4.18

and ΔT the change in temperature for water= 28-25 = 3 ° C

and ΔT the change in temperature for Al = 100-28= 72°C

and M Al is the mass of Al block

C is the specific heat capacity of the block = 0.9 

so by substitution:

100 g * 4.18*3 = M Al * 0.9*72

∴ the mass of Al block is = 100 g *4.18 / 0.9*72

                                          = 19.35 g 






Related Questions


Given the balanced ionic equation representing a reaction:



In this reaction, electrons are transferred from


A)
Al to Mg2+

B)
Al3+ to Mg

C)
Mg to Al3+

D)
Mg 2+ to Al

pls explain

Answers

2Al³⁺ (aq) + 3 Mg⁰ (s) --> 3Mg²⁺ (aq) + 2Al⁰ (s)

Al³⁺  +3e⁻ ------> Al⁰ 
Al had positive charge and them it became neutral, that means that it took 3 negative particles (electrons).    (+3-3=0)
We have 2 Al³⁺, and they take 3*2 =6 electrons

Mg⁰  -----> Mg²⁺ + 2e⁻
Mg was neutral atom, and them it became positive ion, that means it lost electrons .  (0=+2-2)
We have 3Mg, and they loose 2*3=6 electrons.

Mg loose electrons, Al³⁺ takes electrons, that means that electrons are transferred from  Mg to Al³⁺.

Answer is C).

Find the longest wavelengths of light that can cleave the bonds in elemental nitrogen, oxygen, and fluorine. the average bond energy of n―n bond is 945 kj/mol, oxygen is 498 kj/mol, and f―f is 159 kj/mol. give your answers in scientific notation.

Answers

For Nitrogen:
wavelength = NA x h C / bond energy 
                   = 6.022 x 10²³ x 6.626 x 10⁻³⁴ x 3 x 10⁸ / (945 x 10³)
                   = 1.27 x 10⁻⁷ m
For Oxygen::
wavelength = NA x h C / bond energy 
                   = 6.022 x 10²³ x 6.626 x 10⁻³⁴ x 3 x 10⁸ / (498 x 10³)
                   = 2.40 x 10⁻⁷ m
For Fluorine:
wavelength = NA x h C / bond energy 
                   = 6.022 x 10²³ x 6.626 x 10⁻³⁴ x 3 x 10⁸ / (159 x 10³)
                   = 7.52 x 10⁻⁷ m
(NA is Avogadro's number, h is Planck's constant and C is speed of light )

Explanation:

Longest wavelengths of light that can cleave the bonds in elemental nitrogen

Energy to cleave 1 mol N-N bond = 945 kJ/mol = 945000 J/mol

1 mol= [tex]6.022\times 10^{23}[/tex]

Energy to break 1  N-N bond = [tex]\frac{945000 J/mol}{6.022\times 10^{23} mol^{-1}}=1.56\times 10^{-18} J[/tex]

[tex]E=\frac{hc}{\lambda }[/tex]

[tex]\lambda =\frac{6.626\times 10^{-34}J s\times 3\times 10^{8} m/s}{1.56\times 10^{-18} J}=12.74\times 10^{-8} m=127.4 nm[/tex]

Longest wavelengths of light that can cleave the bonds in elemental nitrogen is 127.4 nm.

Similarly

For oxygen:

Energy to cleave 1 mol O-O bond = 498 kJ/mol = 498000 J/mol

Energy to break 1  O-O bond = [tex]\frac{498000 J/mol}{6.022\times 10^{23} mol^{-1}}=8.26\times 10^{-19} J[/tex]

[tex]E=\frac{hc}{\lambda }[/tex]

[tex]\lambda =\frac{6.626\times 10^{-34}J s\times 3\times 10^{8} m/s}{8.26\times 10^{-19} J}=2.406\times 10^{-7}m=240.6 nm[/tex]

Longest wavelengths of light that can cleave the bonds in elemental oxygen is 240.6 nm.

For fluorine

Energy to cleave 1 mol F-Fbond = 159 kJ/mol = 159000 J/mol

Energy to break 1  F-F bond = [tex]\frac{159000 J/mol}{6.022\times 10^{23} mol^{-1}}=2.64\times 10^{-19} J[/tex]

[tex]E=\frac{hc}{\lambda }[/tex]

[tex]\lambda =\frac{6.626\times 10^{-34}J s\times 3\times 10^{8} m/s}{2.64\times 10^{-19} J}=7.529\times 10^{-7}m=752.9 nm[/tex]

Longest wavelengths of light that can cleave the bonds in elemental fluorine is 752.9 nm.

What cycloalkanes are present in a steroid ?

Answers

Steroids are biologically very important compounds. They are made up of more that seventeen carbons. The structure of Steroid is comprised of a fused cycloalkane ring system. The simplest steroid and the main skeleton of all steroids is Gonane.

Gonane is made up of four cycloalkane rings i.e. tetracyclic hydrocarbon ring structure. Among these four rings 3 are cyclohexanes (designated as A, B and C) and one is cyclopentane (Designated as D). These four rings fuse to form a cyclopentaperhydrophenanthrene.

The Nucleus (Gonane) of steroids along with some derivatives are shown below,

Given the reaction: cu(s) + 4hno3(aq) → cu(no3)2(aq) + 2no3(g) + 2h2o(l )as the reaction occurs, what happens to copper?

Answers

When copper reacts with nitric acid, then cooper nitrate, water, and nitrogen dioxide are produced. In this reaction, copper gets oxidized by nitric acid.

What is oxidation?

Oxidation is a type of chemical reaction involving the sharing of electrons and an increase or decrease of the oxidation number. When a chemical species loses an electron, it is said to be oxidized.

The balanced chemical reaction is given as:

Cu(s) + 4HNO₃(aq) → Cu(NO₃)₂(aq) + 2NO₂(g) + 2H₂O(l)

In the reaction, copper forms copper nitrate, and its oxidation changes from 0 to +2. On the other hand, nitrate species get reduced to nitrogen dioxide and change the state from +5 to +4.

Therefore, copper gets oxidized by nitric acid.

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If 2.00 g of mg reacts completely with 50.0 ml of hcl solution, what is the molarity of the hcl solution? mg(s) + 2hcl(aq) → mgcl2(aq) + h2(g)

Answers

The molarity of HCl is calculated as below

find the moles  of   mg used
moles = mass /molar mass

= 2.00g/24 g/mol=0.083 moles
 write the  reacting equation
Mg(s) +2HCl (aq)= MgCl2(aq) + H2(g)

by use of mole ratio between Mg to HCl  which is 1  :2 the moles of HCl is therefore
= 0.083 x2 =0.166 moles

molarity of HCl = moles of HCl/ volume in dm^3

that is 0.166/50 x1000= 3.3 M of HCl
the balanced equation for the reaction between Mg and HCl is as follows;
Mg + 2HCl ---> MgCl₂ + H₂
stoichiometry of Mg to HCl is 1:2
number of moles of Mg reacted - 2.00 x 10⁻³ g / 24 g/mol = 0.0833 x 10⁻³ mol 
according to molar ratio 
number of HCl moles reacted - 0.0833 x 10⁻³ x 2 mol = 0.167 x 10⁻³ mol 
number of HCl moles in 50.0 mL -  0.167 x 10⁻³ mol 
therefore number of HCl moles in 1000 mL -  0.167 x 10⁻³ mol / 0.0500 L 
molarity of HCl - 0.00334 M

Which of the two substances would have the higher boiling point ch4 or c?

Answers

ch4 boiling point: -258.7 F (-161.5 C)
c boiling point: 8,721 F (4,827 C)

therefore: carbon has a higher boiling point

ch4 is also a gas at room temp which is why it’s boiling point is so low.
c is a solid at room temp

Carbon has a higher boiling point than [tex]CH_4[/tex].

What is Boiling Point?

The boiling point of a substance is defined as the temperature at which the vapor pressure of the liquid becomes equal to the pressure surrounding the liquid and the liquid changes into vapor. This point of liquid varies depending on the surrounding environmental pressure.

The boiling point is the temperature at which the pressure exerted by the surroundings on a liquid is equal to the pressure exerted by the liquid's vapor, in which case the liquid changes to vapor without additional heat raising the temperature.

For above given example,

[tex]CH_4[/tex] is a gas at room temperature having a boiling point of -258.7 F (-161.5 C) which is why it’s boiling point is so low while Carbon is a solid at room temperature having a boiling point of 8,721 F (4,827 C)

Thus, Carbon has a higher boiling point than [tex]CH_4[/tex].

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Which is a major factor affecting population growth rate?

Answers

The population of the planet is constantly increasing, and this growth can have many effects on the environment and the economy of the world. For example, as the world population rises, the pressure mounts on the agricultural sector to feed the millions of extra mouths. In predicting the rise of the world population, scientists use a number of variables.


Fertility Rate

The factor which affects the growth of the population in the biggest way is the fertility rate. The fertility rate is typically measured by the number of children per one woman of child-bearing age. If the fertility rate is larger than 2, the rule of thumb is that the population should rise, as there are more children than their parents. On the other hand, if this ratio is below 2, the population of the region may be destined for a decline.

Mortality Rate

A key factor affecting the growth of the population is the death, or mortality, rate. Just as the birth of new people increases the population size, deaths decrease it. The factors that affect the mortality rate include the availability and affordability of quality health care and lifestyle habits – for example, whether they smoke or do physical exercises regularly.


Immigration and Emigration

Cross-border migration is the act of people moving from one country to another. It affects the population size of both the host and destination countries. Emigration is caused by a number of factors, such as fleeing war, finding education, seeking new jobs or joining family members. When a person emigrates from a country, its population shrinks. When someone moves to a country from another place, it is known as immigration. Whether or not a person is allowed to immigrate is controlled by the country that will host this person.

Government Restrictions

There are some people in the world, including politicians, who believe that some countries need to have a birth rate restriction -- in fact, China already has its widely-known one-child policy. Such a restriction would prevent couples from being able to have more than the restricted amount of children. The argument goes that this type of restriction would cause fewer resources to be used and prevent overpopulation.

Final answer:

Population growth rate is affected by several factors, including the birth and death rates, life expectancy, and the age structure of the population. Other factors include human migration and improvements in public health and sanitation.

Explanation:

A major factor affecting population growth rate is the birth and death rates. When birth rates exceed death rates, population size increases. Conversely, when death rates exceed birth rates, population size decreases. Life expectancy also plays an important role. The length of time individuals remain in the population impacts local resources, reproduction, and the overall health of the population.

Another factor is related to the age structure of a population, which is the proportion of a population in different age classes. Rapid growth countries often have a pyramidal age structure, showing many young, reproductive-aged individuals. On the other hand, areas with slow growth or zero growth tend to have a greater proportion of older individuals.

Additionally, other factors affecting human population growth include migration and improvements in public health and sanitation. The development and use of antibiotics and vaccines have decreased the prevalence of infectious disease, allowing human population to grow.

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Identify the lowest energy lewis structure for nitrogen oxide

Answers

Below attachment shows the four possible lewis structures of Nitrogen Oxide (Nitrous Oxide).

Answer:
            Among given Lewis structures, Structure-C has the lowest energy.

Explanation:
                   The greater the stability of any compound the lesser will be its energy. Among different Lewis structures of N₂O or any other compound, the one which comprises of less number of formal charges will be having lesser energy. I have selected structure-C but not Structure-B (as both have same number of formal charges) because in structure-C oxygen has a formal charge of -1. Being more electronegative oxygen tends to attract electrons toward itself. While, in structure-B one of the Nitrogen atom is having -1 charge which is not feasible and makes the structure energetically high.
Final answer:

The lowest energy Lewis structure for nitrogen oxide (NO) involves one nitrogen and one oxygen atom sharing a total of 11 valence electrons with an unpaired electron on Nitrogen. It's an odd-electron molecule with a resonance structure, where the electron distribution is a hybrid average of a single and double bond.

Explanation:

The lowest energy Lewis structure for nitrogen oxide (NO) has one nitrogen atom and one oxygen atom with a total of 11 valence electrons. One of these electrons will remain unpaired, which is typical of chemicals that contain nitrogen. Therefore, the nitrogen has a single unpaired electron, while the oxygen atom is fully paired with two lone pairs and one shared pair.

Nitrogen oxide is an odd-electron molecule, meaning it has an unpaired electron which contributes to its reactive properties. Drawing a correct Lewis structure for such molecules involves the same steps as for other molecules, but there may be some unpaired electrons.

To summarize, nitrogen oxide (NO) has a resonance structure rather than a single Lewis structure, due to the presence of an unpaired electron. The representation of its electron distribution is an average of a single bond and a double bond, illustrated as a resonance hybrid of the individual resonance forms.

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In general, metals react by:

A. gaining valence electrons
B. sharing valence electrons
C. sometimes gaining and sometimes losing valence electrons
D. losing valence electrons

Answers

Hello there,
The answer is D. Losing Valence electrons.

Hope this helped and if you have any more questions please feel free to ask me.
Have a nice day!

Answer: Option (D) is the correct answer.

Explanation:

It is known that metals are the substances which hold excess number of electrons and hence they need to lose electrons in order to gain stability.

For example, potassium is a metal with atomic number 19 and its electronic configuration is 2, 8, 8, 1.

So, it needs to gain stability and hence, it easily loses its one valence  electron to acquire a positive charge as [tex]K^{+}[/tex].

Thus, we can conclude that in general, metals react by losing valence electrons.

How can erosion form new land? (site 2)

Answers

Erosion is essentially the removal of material by a natural force, most commonly this is water or air. This is how new landmass is formed from erosion. The material is just being moved then deposited in a new place. These new pieces of land are called depositional landforms.

Answer:

The procedure by which soil, land, or rock get slowly worn away by the natural elements like wind or water is known as erosion. The landforms refer to the natural characteristics found on the surface of the Earth that exhibit different shape and origin. The landforms can be destroyed and created by erosion.  

The landforms created by the process of erosion are known as fluvial erosion landforms. With the passing of water across the land, the sediments and other kinds of natural debris also get carried with it. With time, the gathering of the debris and sediments generate deposits that ultimately turn into a landform. Some of the examples of fluvial erosion landforms comprise flood plains, sandbars, and levees.  

A student has a 2.123 g sample of a hydrated salt. she heats it to drive off all the water. after heating to constant mass, the salt weighs 1.861 g. the anhydrous salt is copper(ii) phosphate. what is the empirical formula of the hydrated salt?

Answers

the mass of hydrated salt - 2.123 g
mass of anhydrous salt - 1.861 g
mass that has been reduced is the mass of water that has been heated and lost from the compound thereby making the salt anhydrous.
therefore mass of water lost - 2.123 - 1.861 = 0.262 g
number of moles of water lost - 0.262 g / 18 g/mol = 0.0146 mol 
number of moles of salt - 1.861 g / 380.6 g/mol = 0.00490 mol 
molar ratio of moles of water to moles of salt 
molar ratio = 0.146 mol / 0.00490 mol = 2.98 rounded off to 3
for every 1 mol of salt there are 3 moles of water
therefore empirical formula - Cu₃(PO₄)₂.3H₂O


What is the molarity of a solution made by dissolving 8.56 g of sodium acetate in water and diluting to 750.0 ml? the molar mass of sodium acetate is 82.03 g/mol?

Answers

molarity is defined as the number of moles in 1 L of solution
number of moles of sodium acetate is - 8.56 g / 82.03 g/mol = 0.104 mol
number of acetate moles in 750.0 mL - 0.104 mol 
then number of acetate moles in 1000 mL - 0.104 mol / 0.7500 L = 0.139 mol/L
molarity of sodium acetate is 0.139 M

By dissolving 8.56 g of sodium acetate in 750.0 mL of water, we find the molarity of the solution to be 0.1391 M. This calculation involves determining the number of moles and the volume in liters. Dividing the moles of solute by the volume of solution gives the molarity.

To find the molarity of a solution made by dissolving 8.56 g of sodium acetate in water and diluting to 750.0 mL, you first need to determine the number of moles of sodium acetate. The molar mass of sodium acetate (CH3COONa) is 82.03 g/mol.

Number of moles = mass / molar mass

Number of moles = 8.56 g / 82.03 g/mol = 0.1043 moles

Next, convert the volume of the solution from mL to L:

Volume = 750.0 mL = 0.750 L

Finally, calculate the molarity (M) of the solution:

M = moles of solute / liters of solution

M = 0.1043 moles / 0.750 L = 0.1391 M

Therefore, the molarity of the solution is 0.1391 M.

How many atoms are in 1.00 gram of Ag? Express your answer in scientific notation. _____× 10^___ atoms

Answers

 The  number  of atoms in 1.00 grams  of Ag  is calculated as  below

calculate  the moles of Ag = mass/molar mass

=  1g/ 107.87 g/mol= 9.27 x10 ^-3  moles

by use  of Avogadro law  constant 1 mole = 6.02 x10^23 atoms

what  about 9.27 x10 ^-3  moles

= (9.27 x10^-3 moles/ 1mole) x6.02 x10 ^23  atoms  = 5.581  x10^ 21 atoms

A strontium-90 atom that has lost 2 electrons has ________ protons, ________ neutrons, and ________ electrons.

Answers

For an atom, the atomic number is equal to number of protons and number of electrons. Mass number is sum of number of protons and neutrons in nucleus of an atom. Atomic number is denoted by symbol Z and mass number is denoted by symbol A.

The atomic number of strontium is Z=38 and mass number is A=90.

Now, [tex]Z=n_{p}=n_{e}=38[/tex]

Also, [tex]A=n_{p}+n_{n}=90[/tex]

Putting the value of [tex]n_{p}[/tex] in above equation,

[tex]A=38+n_{n}=90[/tex]

Or,

[tex]n_{n}=90-38=52[/tex]

Thus, number of neutrons are 52.

Now, after losing two electrons, number of protons and neutrons remains the same but number of electrons becomes 38-2=36

Therefore, a strontium-90 atom that has lost 2 electrons has 38 protons, 52 neutrons and 36 electrons.

Final answer:

A strontium-90 atom that has lost two electrons has 38 protons, 52 neutrons, and 36 electrons.

Explanation:

A strontium-90 atom originally has 38 protons, 52 neutrons, and 38 electrons. If it has lost 2 electrons, then it has 36 electrons left. So, a strontium-90 atom that has lost 2 electrons has 38 protons, 52 neutrons, and 36 electrons. The atomic number of strontium is 38, which tells us its number of protons, and by subtracting this number from the atomic mass, we get the number of neutrons. The number of electrons in a neutral atom should be equal to the number of protons, but if the atom becomes an ion and loses electrons in the process, the number of electrons decreases.

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Draw any one of the skeletal structures of a 2° alkyl bromide having the molecular formula of c6h13br and two stereogenic centers. indicate chirality by using wedge and hashed wedge notation. lone pairs do not need to be shown.

Answers

Check the following picture: 

The  skeletal structures of a 2° alkyl bromide with two  stereogenic centers is shown below.

What are the stereogenic centers in 2° alkyl bromide ?

A carbon atom in a molecule that is linked to four separate substituents is referred to as a stereogenic center, also referred to as a chiral center. Because secondary carbon atoms normally have two identical alkyl groups and two hydrogen atoms linked to them.

The two of the substituents (two alkyl groups) are the same. Tetrahedral carbon compounds with four distinct substituents are frequently where chirality occurs.

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At a certain temperature and pressure, 0.20 mol of carbon dioxide has a volume of 3.1 L. A 3.1-L sample of hydrogen at the same temperature and pressure ____.

Answers

Answer:
            A 3.1 L sample of hydrogen at the same temperature and pressure contains the same number of molecules.

Explanation:
                   As we know ;"1 mole of any gas at STP occupies exactly 22.4 L of volume". Therefore, CO₂ and H₂ gas having same number of moles (0.20 moles) will occupy exactly the same volume.

Now, converting moles into number of molecules,

# of Molecules  =  Moles × 6.022 × 10²³

Putting value of mole,

# of Molecules  =  0.2 mol × 6.022 × 10²³ molecules.mol⁻¹

# of Molecules  =  1.20 × 10²³ molecules

Hence, both gases will contain 1.20 × 10²³ molecules.

A 3.1 L sample of hydrogen at the same temperature and pressure as 0.20 mol of CO₂ will also contain 0.20 mol of hydrogen.

To answer the question, we need to understand the relationship between volume, temperature, and pressure for gases, as explained by the Ideal Gas Law.

The Ideal Gas Law is given by the equation PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature in Kelvin.

Since we are told that the volume sample of hydrogen is at the same temperature and pressure as the carbon dioxide, we can directly relate the two based on their moles.

For carbon dioxide (CO₂):

n = 0.20 mol

V = 3.1 L

This relationship tells us that 0.20 moles of CO₂ occupies 3.1 L at the given temperature and pressure.

Applying the same conditions to hydrogen (H₂), a 3.1 L sample of hydrogen gas will contain the same number of moles as the CO₂ under the same conditions:

0.20 mol of Hydrogen (H₂)

Therefore, 3.1 L of hydrogen at the same temperature and pressure will also contain 0.20 mol of hydrogen gas.

A sample of he gas (2.35 mol) occupies 57.9 l at 300.0 k and 1.00 atm. the volume of this sample is _____ l at 423 k and 1.00 atm.

Answers

The  volume  of  the sample  at 423 k  and 1.00 atm  is calculated using  Charles  law  formula   that is V1/T1 =V2/T2 since  the  pressure is  constant

V1=75.9  L
T1=  300 K
V2=?
T2=423 k

by   making the V2 the  subject  of  the formula

V2=T2V1/T1
V2=  57.9 L  x 423 K/300 K=  81.64 L  is the volume of the  sample

The ideal gas relates to the pressure, temperature, pressure, and mole of the gas. The volume of the sample at 423 K and 1 atm is 81.64L.

What is Charles's law?

Charles law gave the relation between the temperature and the volume of gas. According to him, the volume of the gas is directly proportional to the temperature of the gas.

Given,

Initial volume = 75.9 L

Initial temperature = 300 K

Final volume = ?

Final temperature = 423 K

The relation between the temperature and the volume of the two gases is shown as:

[tex]\rm \dfrac{V_{1}}{T_{1}} = \rm \dfrac{V_{2}}{T_{2}}[/tex]

Substituting values in the above equation:

[tex]\begin{aligned}\rm V_{2}& = \rm \dfrac{T_{2}V_{1}}{T_{1}}\\\\&= \dfrac{57.9\times 423}{300}\\\\&= 81.64 \;\rm L \end{aligned}[/tex]

Therefore, 81.64 L is the final volume at 423 K.

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Which statement best describes how activation energy influences a reaction?

Answers

The correct answer is:
The greater the activation energy, the lower the reaction rate.


Activation energy simply means the minimum amount of energy needed for the particles to have a successful reaction when they collide. There are two basic factors necessary for a reaction to just take place.

Particles need to collide with each other with minimum amount of energry.They must hit each other in proper orientation. If the particles are colliding each other at proper orientation but not with sufficient energy, then reaction will not take place. Higher activation energy means that more energy will be required for the particles to have a successful collision. Like, combustion. It is generally an exo reaction but still needs heat. It is because activation energy is high. Heat causes particles to gain enough energy to overcome the activation energy barrier. So basically, higher activation energy means slow rate and lower means higher rate

1. Which of the following statements about mechanical waves is true?
a. mechanical waves require a medium to travel through
b. mechanical waves do not have amplitude and wavelength
c. mechanical waves do not have frequency
d. mechanical waves can travel through blank space

2. Which waves have the shortest wavelength and highest energy on electromagnetic spectrum?
a. microwaves
b. x-rays
c. infrared
c. gamma rays

3. What is true about infrared and X-Rays?
a. X-Rays have greater longer wavelength than infrared
b. Infrared have shorter wavelength than x-rays
c. x-rays have lower energy than infrared
d. Infrared have lower frequency than x-rays

4. In a longitudinal wave (compression wave_ the particles of a matter move ______
a. perpendicular (at right angles)
b. in a circular direction
c. backwards
d. parallel

5. In regard to spend of sound, sound travels slowest in ____
a. solids
b.liquids
c. gases

Answers

1. The answer is "a".


Mechanical waves require a medium to travel. If there is no medium, the mechanical wave doesn't travel. Since, they are waves; they have a wavelength, frequency, speed and also amplitude. The speed depends on the medium and type of the wave. An example for the mechanical waves is sound wave.


2. E = hf, where E is energy, h is plank constant and f is the frequency. Hence, if the frequency is high, then the energy is high. 


v = fλ , where v is the speed, f is the frequency and λ is the wavelength. If the frequency is high, then the wavelength is low.


According to the given choices, gamma rays have the shortest wavelength and highest energy on electromagnetic spectrum.


3. The wavelength of X-rays are smaller the wavelength of infrared.

According to the v=fλ, lower the wavelength, then higher the frequency.  According to the E = hf, if the frequency is high, then the energy is also high. 


Hence, the correct answer is "d"


4. In a longitudinal wave (compression wave) the particles of a matter move parallel


There are two types of waves according to the particle movement. They are transverse waves and longitudinal waves. In transverse waves, the particles of the medium move perpendicular to the direction of the wave and longitudinal waves have parallel movement of particles to the direction of wave.


5. In regard to spend of sound, sound travels slowest in gases.

 

Solids have the highest speed of sound while gases have the lowest. This is because of the particle arrangement of each phase. Solid phase has very tightly packed particle arrangement and due to that the transfer of sound wave in easy than in gases.

Which pair of atoms forms a nonpolar covalent bond? which pair of atoms forms a nonpolar covalent bond? na and cl c and o n and cl b and o?

Answers

Final answer:

Boron and Oxygen, due to their similar electronegativity can form a nonpolar covalent bond. This type of bond is formed when electrons are shared equally between atoms. Sodium and Chlorine, with their contrasting electronegativities, would rather form an ionic bond.

Explanation:

The atom pairs that form a nonpolar covalent bond from the options given would be B and O. Boron (B) and Oxygen (O) come from nonmetals with similar electronegativity, hence they share electrons equally forming a nonpolar covalent bond.

Nonpolar covalent bonds form when two atoms share electrons equally, meaning the electrons spend an equal amount of time around each atom. This could involve two atoms of the same element, like O₂, or atoms of different elements with similar electronegativity, like CH4 (methane).

On the contrary, atoms like Sodium (Na) and Chlorine (Cl), have a large difference in electronegativity, leading to an ionic bond instead of a covalent bond. In such cases, a clearly positive (cation) or negative (anion) charge develops on the atoms.

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The correct answer is: E) None of the above  atoms form a nonpolar covalent bond.

For a nonpolar covalent bond to form, the atoms involved must have similar electronegativities, typically seen in diatomic molecules of the same element

Given options:

A) Na and Cl - This forms an ionic bond.

B) C and O - This forms a polar covalent bond.

C) N and Cl - This forms a polar covalent bond.

D) B and O - This forms a polar covalent bond.

Full question

Which pair of atoms forms a nonpolar covalent bond?

A) Na and Cl  

B) C and O  

C) N and Cl  

D) B and O

E) None of the above.

Which of the pairs of compounds below is most likely to form a solution when mixed?view available hint(s)which of the pairs of compounds below is most likely to form a solution when mixed?water and ammonia (nh3)sodium chloride (nacl) and pentane (c5h12)?

Answers

Answer:
             Water and Ammonia will form Solution.

Explanation:

Solution is a Homogeneous mixture of two or more components. The solute present in the solvent can not be distinguished neither microscopically nor visually. This formation of Homogeneous mixture usually takes place due to greater intermolecular interactions between the Solute and Solvent. Hence, in given scenario we are not given with the amount of components, therefore we can decide on the basis of interactions between the components. 
 
In case of Water and Ammonia there exist a stronger type of intermolecular interactions called as Hydrogen Bond Interactions as in both compounds Hydrogen atoms are attached to more electronegative atoms like Oxygen and Nitrogen. Hence, as Like Dissolves Like, so these two components will form a Solution.

While in second case, Pentane is a non polar compound while Sodium Chloride is an ionic compound with positive Na and negative Cl. So, these two compounds cannot interact with each other, Hence will fail to form a solution and results in the formation of Suspension. 

Answer: water and ammonia or (NH3)

Which of the following phase changes would release energy as it occurs? (4 points) Melting
Boiling
Evaporating
Freezing

Answers

I believe it is freezing.

When the pressure that a gas exerts on a sealed container changes from 22.5 psi to ? psi, the temperature changes from 110 degrees celcius to 65.0 degrees celcius?

Answers

Using Gay-Lussac's Law, pressure is proportional to (absolute) temperature in Kelvin. We first convert the temperature values to Kelvin: 110 C = 383.15 K, while 65 C = 338.15 K.
P1/T1 = P2/T2
22.5/383.15 = P2/338.15
P2 = 19.9 psi

Answer:19.9

Explanation: make sure correct significant figures with psi

When heated, calcium carbonate decomposes to yield calcium oxide and carbon dioxide gas via the reaction caco3(s)→cao(s)+co2(g) what is the mass of calcium carbonate needed to produce 61.0 l of carbon dioxide at stp? express your answer with the appropriate units?

Answers

Answer is: 227.3 grams of of calcium carbonate needed.
Chemical reaction: CaCO₃ → CaO + CO₂.
V(CO₂) = 61.0 L.
n(CO₂) = V(CO₂) ÷ Vm.
n(CO₂) = 61 L ÷ 22.4 L/mol.
n(CO₂) = 2.723 mol.
From chemical reaction: n(CO₂) : n(CaCO₃) = 1 : 1.
n(CaCO₃) = 2.273 mol.
m(CaCO₃) = n(CaCO₃) · M(CaCO₃).
m(CaCO₃) = 2.273 mol · 100 g/mol.
m(CaCO₃) = 227.3 g.

For producing 61 L of [tex]\rm CO_2[/tex], 227.23 grams of  [tex]\rm CaCO_3[/tex]. is required.

Any gas occupies 22.4 L/mol space at STP.

So, 61.0 L of gas will be;

Moles of [tex]\rm CO_2[/tex] = [tex]\rm \frac{61.0}{22.4}[/tex]

Moles of  [tex]\rm CO_2[/tex] = 2.723 moles

From the reaction,

1 mole of [tex]\rm CO_2[/tex] has been produced by 1 mole of [tex]\rm CaCO_3[/tex].

2.723 moles of [tex]\rm CO_2[/tex] has been produced by 2.723 mole of [tex]\rm CaCO_3[/tex].

Mass = [tex]\rm moles\;\times\;molecular\;weight[/tex]

Mass of [tex]\rm CaCO_3[/tex]. = 2.723 [tex]\times[/tex] 100

Mass of [tex]\rm CaCO_3[/tex]. = 227.23 grams.

For producing 61 L of [tex]\rm CO_2[/tex], 227.23 grams of  [tex]\rm CaCO_3[/tex]. is required.

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What is the average kinetic energy kavg of the hydrogen molecules at a temperature of 100k? assume that the molecules have only three degrees of freedom at this temperature?

Answers

The average kinetic energy of hydrogen molecules at 100 K with three degrees of freedom can be calculated using the formula kavg = 3/2 * k * T, where k is Boltzmann's constant and T is the temperature in Kelvin.

The average kinetic energy kavg of hydrogen molecules at a temperature of 100 K with three degrees of freedom can be calculated using the formula:

kavg = 3/2 * k * T

where k is Boltzmann's constant (1.38 x 10^-23 J/K) and T is the temperature in Kelvin. Plugging in the values:

kavg = 3/2 * 1.38 x [tex]10^{-23}[/tex] J/K * 100 Kkavg = 2.07 x [tex]10^{-21}[/tex] J

Using oxidation and reduction half-reactions, balance the skeletal equation cl2o7(g) + h2o2(aq) → clo− 2 (aq) + o2(g) of the production of chlorite ions from dichlorine heptoxide. the reaction takes place in a basic solution. what is the smallest possible integer coefficient of o2 in the combined balanced equation?

Answers

Final answer:

In order to balance the equation, we identify the oxidation and reduction half-reactions and then combine them. The smallest possible integer coefficient of O₂ in the balanced equation is 10.

Explanation:

To balance the given equation cl2o7(g) + h2o2(aq) → clo− 2 (aq) + o2(g), we first have to identify the oxidation and reduction half-reactions. The oxidation half-reaction is: Cl₂O₇ → 2ClO₂⁻ + 5/2O₂. The reduction half-reaction is: H₂O₂ + 2e⁻ → 2OH⁻. Then, we combine the oxidation and reduction half-reactions: 4 Cl₂O₇ + H₂O₂ → 8 ClO₂⁻ + 2OH⁻ + 10O₂. The smallest possible integer coefficient of O₂ in the combined balanced equation is 10.

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Final answer:

The process of balancing redox reactions involves separating the reaction into two half-reactions, balancing them individually, and then combining them to ensure the total charges cancel out. In the given reaction, Cl2O7(g) + H2O2(aq) → ClO2−(aq) + O2(g), the smallest possible integer coefficient of O2 is 1 as one molecule of H2O2 produces one molecule of O2.

Explanation:

To balance the given redox reaction, Cl2O7(g) + H2O2(aq) → ClO− 2(aq) + O2(g), we split into two half-reactions, one for oxidation, and one for reduction. Assign oxidation numbers to identify which atoms have changed oxidation state during the reaction. The oxidation half-reaction can be identified as H2O2(aq) → O2(g) and the reduction half-reaction as Cl2O7(g)  → ClO− 2(aq).

Balance each of these half-reactions, first for atoms other than hydrogen and oxygen, then for oxygen, then for hydrogen, and lastly for charge. After balancing the half-reactions individually, combine them ensuring the total charges cancel out. The smallest integer coefficient of O2 in balanced equation results from the oxidation half-reaction, where one molecule of H2O2 produces one molecule of O2, thus the smallest possible integer coefficient of O2 is 1.

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Determine the overall charge on each complex tetraquadichlorochromium (iii)

Answers

Answer:
             +1

Explanation:
                   Molecular Formula of Tetraquadichlorochromium (III) is as follow,

                                               [Cr(H₂O)₄Cl₂]ˣ

The oxidation states of elements present in complex are,

                                  H₂O  =  0     (Neutral Ligand)

                                  Cl  =  -1

                                  Cr  =  +3      (Given)

                                  x  =  Overall charge
So,
                                 [+3 + (0)₄ + (-1)₂]  =  x

                                 [+3 - 2]  =  x

                                          x  =  +1

Result:
            
Overall charge on Tetraquadichlorochromium (III) is +1.

How much 0.100 m hcl is required to completely neutralize 20.0 ml of 0.250 m naoh?

Answers

the balanced equation for the reaction between NaOH and HCl is as follows
NaOH + HCl ---> NaCl + H₂O
stoichiometry of NaOH to HCl is 1:1
number of NaOH moles reacted - 0.250 mol/L x 0.0200 L = 0.005 mol 
therefore number of HCl moles reacted - 0.005 mol 
molarity of given HCl solution - 0.100 M
number of HCl moles in 1 L - 0.100 mol 
then 0.005 mol of HCl in - 0.005 mol / 0.100 mol/L = 50.0 mL
volume of HCl required is 50.0 mL
Final answer:

To neutralize 20.0 mL of 0.250 M NaOH, you will need 50.0 mL of 0.100 M HCl.

Explanation:

To determine how much 0.100 M HCl is required to neutralize 20.0 mL of 0.250 M NaOH, we can use the balanced equation for the reaction between HCl and NaOH: HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq). The mole ratio between HCl and NaOH is 1:1, meaning that 1 mole of HCl reacts with 1 mole of NaOH. We can use this ratio to calculate the amount of HCl needed.

First, find the number of moles of NaOH:

0.250 M NaOH x 0.0200 L = 0.005 moles NaOH

Since the mole ratio between HCl and NaOH is 1:1, we need 0.005 moles of HCl to neutralize the NaOH.

Now, calculate the volume of 0.100 M HCl needed to contain 0.005 moles:

0.005 mol HCl / 0.100 mol/L = 0.050 L = 50.0 mL

Therefore, 50.0 mL of 0.100 M HCl is required to completely neutralize 20.0 mL of 0.250 M NaOH.

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What is the percent of MgSO4 in magnesium sulfate heptahydrate?
48.83 %
51.17 %
95.43 %
86.98 %

Answers


one mole of MgSO4.7H2O weighs 246.4696 g 

in that one mole are seven moles of H2O, weighing 126.1036 g 

The percentage of water is this calculation: 

(126.1036 / 246.4696) * 100 = 51.17%

Use appropriate data to calculate δg∘ for the reaction. 2mno−4(aq)+cd(s)→2mno2−4(aq)+cd2+(aq) express your answer to three significant figures and include the appropriate units.

Answers

Reaction at anode: Cd    →     Cd2+    +     2e-, Eo = -0.403 v
Reaction at cathode:     2MnO4-   +    2e-     →      MnO4^2-, Eo = 1.5 v

Net reaction: Cd  +   2MnO4-    ⇆     Cd2+     +     MnO4^2-

Net cell representation: Cd/Cd2+// MnO4-/MnO4^2-

Now, standard EMF of cell = E(o)cell = Er - El
                                                            = 1.5 - (-0.403)
                                                            = 1.903 v

Now, ΔGo = -nFE(o)cell
where n = number of electrons = 2
F = faraday's constant = 96500

ΔGo = - 2 X 96500 X 1.903
         = 367.27 kJ

Answer:

∆G° = -185 kJ

Explanation:

First, use the half-reaction method:

OX: Cd ⟶ Cd2+ + 2e- where E° = -0.40 V (anode)

RED: 2MnO-4 + e- ⟶ 2MnO2-4 where E° = 0.56 V (cathode)

Balance the chemical equation with the correct stoichiometric coefficients:

2 × (2MnO-4 + e- ⟶ 2MnO2-4) = 4MnO-4 + 2e- ⟶ 4MnO2-4

1 × (Cd ⟶ Cd2+ + 2e-) = Cd ⟶ Cd2+ + 2e-

Cancel out e- on both sides to get:

4MnO-4 + Cd ⟶ 4MnO2-4 + Cd2+

Using this balanced equation, we can determine:

number of moles of electrons exchanged in the cell reaction, n = 2

E°cell = E°cathode - E°anode = 0.56 - (-0.40) = 0.96 V

F, Faraday's constant: 96485 / mol e-

∆G° = -nFE°cell = -(2)(96485)(0.96)

∆G° = -185251.2 J = -185 kJ

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