Which of the following always occurs in a
chemical reaction?

A) a gas is given off.
B) a solid is produced,
C) a new substance is produced.
D) a colour change takes place.

Answer:

Percent by mass of solute is (10/35) x 100 =  28.57%

Percent by mass of solvent is (25/35) x 100 = 71.43%

Explanation:

10.0 grams of solute

25.0 grams of solvent

Total Mass = 35 grams

percent by mass = (Mass A / Total Mass) x 100

Percent by mass of solute is (10/35) x 100 =  28.57%

Percent by mass of solvent is (25/35) x 100 = 71.43%

Answer:

Solid

Explanation:

Solid has a definite shape and its molecules have high density.

Hope this will help you.

Answer:

The HWA attacks eastern hemlock trees in forests and ornamental hemlock trees found in our residential landscaping. It feeds on the hemlock trees' young twigs by sucking the sap, causing their buds to die and needles to dry out and drop from the plant prematurely i think

hope i helped!!

Answer:

B. 225 W

Explanation:

Power is the measure of the amount of work done in a certain time frame. It can be found using the following formula.

p=w/t

where w is the amount of work done in joules and t is the amount of time in seconds.

We know that 900 joules of work was done in 4 seconds.

w=900 J

t= 4 s

Substitute these values into the formula.

p=900 J/ 4 s

Divide 900 by 4

900/4=225

p= 225 J/s

1 Joules of work per second (J/s) is equal to 1 Watt (W). Therefore, we can substitute Watts for Joules per second.

p= 225 Watts

The power is 225 Watts, and the correct answer is B.

Answer:

they meen like what youve learned or like what youve been tonight....all that is work stuff you did for example school work.

Answer:

None of them, answer seems to be 24 unless I messed up

Explanation:

How many electrons appear in the balanced equation

What the heck do they mean, do they mean transferred?

N2O5 --> NH4+

Left Side

N 5+  Electrons 2 in central shell, 5 in outer

O 2- Electrons 2 in central shell, 6 in outer

Right Side

H  1+ Electrons 1 in central shell

N 3- Electrons 2 in central shell, 5 in outer

Hmm, ok so need to balance the half equation first, this is a redox reaction.

Hmm, so it's going to be something like

H2 + N2O5 → NH + O3  

Step 1. Write down the unbalanced equation ('skeleton equation') of the chemical reaction. All reactants and products must be known. For a better result write the reaction in ionic form.

H2 + N2O5 → NH + O3  

Step 2. Separate the process into half reactions. A redox reaction is nothing but both oxidation and reduction reactions taking place simultaneously.

a) Assign oxidation numbers for each atom in the equation. Oxidation number (also called oxidation state) is a measure of the degree of oxidation of an atom in a substance (see: Rules for assigning oxidation numbers).

H02 + N+52O-25 → N-1H+1 + O03  

b) Identify and write out all redox couples in reaction. Identify which reactants are being oxidized (the oxidation number increases when it reacts) and which are being reduced (the oxidation number goes down). Write down the transfer of electrons. Carefully, insert coefficients, if necessary, to make the numbers of oxidized and reduced atoms equal on the two sides of each redox couples.

When one member of the redox couple is oxygen with an oxidation state of -2 or hydrogen with an oxidation state of +1, it is best to replace it with a water molecule.

O:3H+12O-2 → O03 + 6e-(O)

H02 → H+12O-2 + 2e-(H)

R:N+52O-25 + 12e- → 2N-1H+1(N)

c) Combine these redox couples into two half-reactions: one for the oxidation, and one for the reduction (see: Divide the redox reaction into two half-reactions).

O:3H+12O-2 + H02 → O03 + H+12O-2 + 8e-  

R:N+52O-25 + 12e- → 2N-1H+1  

Step 3. Balance the atoms in each half reaction. A chemical equation must have the same number of atoms of each element on both sides of the equation. Add appropriate coefficients (stoichiometric coefficients) in front of the chemical formulas to balance the number of atoms. Never change any formulas.

a) Balance all other atoms except hydrogen and oxygen. We can use any of the species that appear in the skeleton equations for this purpose. Keep in mind that reactants should be added only to the left side of the equation and products to the right.

O:3H+12O-2 + H02 → O03 + H+12O-2 + 8e-  

R:N+52O-25 + 12e- → 2N-1H+1  

b) Balance the charge. For reactions in an acidic solution, balance the charge so that both sides have the same total charge by adding a H+ ion to the side deficient in positive charge.

O:3H+12O-2 + H02 → O03 + H+12O-2 + 8e- + 8H+  

R:N+52O-25 + 12e- + 12H+ → 2N-1H+1  

c) Balance the oxygen atoms. Check if there are the same numbers of oxygen atoms on the left and right side, if they aren't equilibrate these atoms by adding water molecules.

O:3H+12O-2 + H02 + H2O → O03 + H+12O-2 + 8e- + 8H+  

R:N+52O-25 + 12e- + 12H+ → 2N-1H+1 + 5H2O  

Balanced half-reactions are well tabulated in handbooks and on the web in a 'Tables of standard electrode potentials'. These tables, by convention, contain the half-cell potentials for reduction. To make the oxidation reaction, simply reverse the reduction reaction and change the sign on the E1/2 value.

Step 4. Make electron gain equivalent to electron lost. The electrons lost in the oxidation half-reaction must be equal the electrons gained in the reduction half-reaction. To make the two equal, multiply the coefficients of all species by integers producing the lowest common multiple between the half-reactions.

O:3H+12O-2 + H02 + H2O → O03 + H+12O-2 + 8e- + 8H+| *3

R:N+52O-25 + 12e- + 12H+ → 2N-1H+1 + 5H2O| *2

O:9H+12O-2 + 3H02 + 3H2O → 3O03 + 3H+12O-2 + 24e- + 24H+  

R:2N+52O-25 + 24e- + 24H+ → 4N-1H+1 + 10H2O  

Step 5. Add the half-reactions together. The two half-reactions can be combined just like two algebraic equations, with the arrow serving as the equals sign. Recombine the two half-reactions by adding all the reactants together on one side and all of the products together on the other side.

9H+12O-2 + 2N+52O-25 + 3H02 + 24e- + 3H2O + 24H+ → 3O03 + 4N-1H+1 + 13H2O + 24e- + 24H+

Step 6. Simplify the equation. The same species on opposite sides of the arrow can be canceled. Write the equation so that the coefficients are the smallest set of integers possible.

2N+52O-25 + 3H02 → 3O03 + 4N-1H+1 + H2O

Answer:

they move faster

Explanation:

Answer:

They move faster.

Answer:

A

Explanation:

Hmm, so we have the following in the diagram

Pt(s)

Cl2(g)

Ag(s)

NaCl(aq)

AgNO3(aq)

Pt 2+, 4+, 6+  Though it states Pt is inert

Cl 2-

Ag 1+

Na 1+

NO3-

Anode definition: the positively charged electrode by which the electrons leave an electrical device.

Electrode definition: a conductor through which electricity enters or leaves an object, substance, or region.

Cations attracted to cathode pick up electrons

Anions attracted to anode release electrodes+

Reduction at Cathode (red cat gain of e)

Oxidation at Anode (ox anode loss of e)

So from the diagram we can see that the charge is being generated through the 2 metal plates.

So the answer is A, the anode material is Pt and the half reaction is 2Cl- = Cl2 + 2e-

Answer:

It's the bottom layer.  

Explanation:

Scientists use the Law of Superposition to determine the relative age of a layer of sedimentary rock:

The oldest rock layer is at the bottom of an undisturbed bed.

Thus, Layer A in the figure below was deposited first.

Answer:

0 C.

Explanation:

Answer:

Fuels made from oil mixtures containing large hydrocarbon molecules are not efficient as they do not flow easily and are difficult to ignite. Crude oil often contains too many large hydrocarbon molecules and not enough small hydrocarbon molecules to meet demand. This is where cracking comes in

Explanation:

Answer:

Reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.RT

Explanation:

Answer:

I found on internet may be it helps

Explanation:

Here, we provide a general review of recent studies into the genetic basis of human brain evolution. The insights gleaned from these studies can be broadly divided into three categories: (i) positive selection on protein-coding regions of the genome that lead to changes in the sequences of existing proteins; (ii) duplication and deletion of genes; and (iii) evolutionary changes in non-coding regions of the genome, especially those in cis-regulatory sequences that lead to altered gene expression .

Answer:

-4

Explanation:

[tex]log 10^{-4} = -4 log 10[/tex]

log 10 = 1

Therefore -4 log 10 = -4 x 1 = -4

Answer:

Can you explain a little bit more?

Explanation:

Answer:

limited resources

Explanation:

nonrenewable resources are those resources found inside the earth that are in a fixed amount. They are being used at a faster rate, and cannot be renewed. These resources include fossil fuels,natural gas, and coal.

// have a great day //

Answer:

copper(ll) carbonate

Explanation:

Since the product is a salt which is copper(II) carbonate, water and carbon dioxide, this reaction is an acid + metal carbonate reaction.

Looking at the salt, Cu²⁺ has to be part of the reactants.

Hence, the missing compound there has to be copper(ll) carbonate, CuCO₃.

The balanced chemical equation would be:

CuCO₃ + 2HNO₃➙ Cu(NO₃)₂ +H₂O +CO₂

P.s. You left out CO₂ as a product in Q2 ;)

Just a recap of the main reactions you would've learnt:

1) Acid + base/ alkali ➙ salt + water

2) Acid + metal ➙ salt + hydrogen gas

3) Acid + metal carbonate ➙ salt + H₂O + CO₂

Answer:

The new pressure is 3164.58 psi.

Explanation:

We have,

Initial pressure, [tex]P_1= 2975\ psi[/tex]

Initial temperature, [tex]T_1=25^{\circ}=298.15\ K[/tex]

The tank is left in a car in the  hot sun and the temperature increases to 44°C, [tex]T_2=44^{\circ} =317.15\ K[/tex]

Let [tex]P_2[/tex] is the final pressure in the tank. Gay Lussac's law,

[tex]P\propto T\\\\\dfrac{P_1}{P_2}=\dfrac{T_1}{T_2}\\\\P_2=\dfrac{P_1T_2}{T_1}[/tex]

Plugging all the values,

[tex]P_2=\dfrac{2975\times 317.15}{298.15}\\\\P_2=3164.58\ psi[/tex]

So, the new pressure is 3164.58 psi.

Answer:

Intake, compression, power, and exhaust

Explanation:

A four-stroke cycle engine is an internal combustion engine that utilizes four distinct piston strokes (intake, compression, power, and exhaust) to complete one operating cycle. The piston make two complete passes in the cylinder to complete one operating cycle.

The sequence of a single complete engine cycle is Intake, compression, power, exhaust. Therefore option 1 is correct.

1. Intake: In this step, the intake valve opens, allowing a mixture of air and fuel to enter the combustion chamber.

2. Compression: After the intake stroke, the intake valve closes, and the piston moves back up, compressing the air-fuel mixture. This compression increases the pressure and temperature inside the cylinder, preparing it for combustion.

3. Power: Once the air-fuel mixture is compressed, the spark plug ignites it. The burning mixture rapidly expands, generating a high-pressure force that pushes the piston down.

4. Exhaust: After the power stroke, the exhaust valve opens, and the piston moves back up, pushing the burned gases out of the cylinder and into the exhaust system.

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Answer: nucleus

Explanation: the bigger the nucleus there more reactive the atom is

Answer:

The larger an atom is, the more reactive it will be.

It helps to think about the size of an atom with the location of the electrons and nucleus in mind. You know that protons are positively charged and electrons are negatively charged, therefore there is a level of attraction between these two oppositely charged subatomic particles. This attraction helps stabilize the atom.

Now, in a larger atom, with more electrons are those electrons (specifically the valence electrons) going to be closer or further from the nucleus than in a smaller atom?

They will of course be further from the nucleus and therefore further from the positively charged nucleus. This makes it easier for the valence electrons to leave the atom and form an ionic bond or to interact with another atom to form a covalent bond.

If electrons can leave more easily, then the atom is more likely to react.

Answer:

22.6881 Grams of CO

Explanation:

Fe2O3 + 3CO = 3CO2 + 2Fe

Ratio

1:3 = 3:2

How many grams of CO are needed to produce 30.2 grams of Fe

Fe2O3 Molar mass: 159.69 g/mol

CO Molar mass: 28.01 g/mol

Fe Atomic mass: 55.845

Ok so our end result is 30.2 Grams of Fe, we have 2 Fe so we have 15.1 Grams per Fe

15.1/55.845 = 0.27

So then we multiply this by 3 as we we know the ratio and get get 0.81 required as this is 3CO.

So we need 0.81 Moles of CO so we need 22.6881 Grams of CO.

Answer:

98.6%

Explanation:

First we put down the equation representing the decomposition of sodium bicarbonate.

2NaHCO3(s) ----> Na2CO3(s) + H2O(l) + CO2(g)

We can see from the data provided that the mass of sodium bicarbonate reacted is 3.01 g.

The number of moles of sodium bicarbonate reacted= mass of sodium bicarbonate/ molar mass of sodium bicarbonate

Molar mass of sodium bicarbonate= 84.007 g/mol

Number of moles of sodium bicarbonate=3.01 g/ 84.007 g/mol

Number of moles of sodium bicarbonate= 0.0358 moles

From the balanced reaction equation,

2 moles of sodium bicarbonate yields 1 mole of sodium carbonate

Hence 0.0358 moles of sodium bicarbonate yields 0.0358/2 = 0.0179 moles of sodium carbonate

Theoretical yield of sodium carbonate = number of moles of sodium carbonate × molar mass of sodium carbonate

Molar mass of sodium carbonate= 105.9888 g/mol

Theoretical yield of sodium carbonate= 0.0179 moles × 105.9888 g/mol

Theoretical yield of sodium carbonate= 1.897 g

Actual yield of sodium carbonate= 1.87 g

%yield of sodium carbonate= 1.87/1.897 ×100

%yield of sodium carbonate= 98.6%

Answer:

The statement is true.

Explanation:

The different means by which the energy is transferred is commonly termed to be 'wave'.

Wave refers to the disturbance transmission from a specific point to another. Different sources are involved in this transmission. The vibration of particles helps in the flow of energy from one medium to another. Vibration leads to the formation of kinetic energy flowing from one medium to another.

Answer:

no

Explanation:

Homogeneous means that the substance looks uniform throughout. This means that all of it looks the same (ex. juice or water). Because you can see the different parts of raisin bran cereal with milk it is not homogeneous, it is heterogeneous.

Answer:

Ammonia accepts a proton from water

Explanation:

Let us quickly remind ourselves of the Brownstead-Lowry definition of an acid. According to Brownstd-Lowry, an acid is any substance that donates hydrogen ions while a base is any substance that accepts hydrogen ions. The hydrogen ion is also known as a proton.

If we look at the behaviour of ammonia in water;

NH3(g) + H2O(l) ----> NH4^+(aq) + OH^-(aq)

We can easily see that ammonia accepts a proton from water (this makes it a Brownstd-Lowry base) and the hydroxide ion is formed in the process. Water functions as the proton donor here.

Answer:

T = 9.875K

Explanation:

The ideal gas Law is PV = nRT.

P = Pressure

V = Volume

n = amount of substance

R =  8.314 J/(K. mol)

T = Temperature in Kelvin

22g CO2

CO2 Molar Mass = 44g/mol

C = 12g/mol

O = 16g/mol

P = 0.8210atm

V = 50L

PV = nRT

0.8210 x 50 = 8.314 x 0.5 x T

41.05 =  4.157T

T = 41.05/4.157

T = 9.875K

Answer:

After one-half life: 16 mg

After 2-half lives: 8 mg

After 3-half lives: 4 mg

After 4-half lives: 2 mg

After 5-half lives: 1 mg

(5 half-lives) x (8 days/half-life) = 40 days  

or doing it the mathematical way:  Let z be the number of days to be found:

1 mg = 32 mg x (1/2)^(z / 8 days)  

1/32 = (1/2)^(z / 8 days)  

log (1/32) = (z / 8 days) x log (1/2)  

z / 8 days = log (1/32) / log (1/2)

z = 8 days x log (1/32) / log (1/2) = 40 days

Explanation:

Iodine-131 has a half-life of 8 days, then it would it take for the number of unstable nuclei in the sample to be reduced from 1,000 to 125 is 512 days.

Total time of the reduction of any substance from an initial concentration to a particular concentration will be calculated as:

T = (t)ⁿ, where

n = number of half lives

t = half life time = 8 days

1st half life: 1000 → 500

2nd half life: 500 → 250

3rd half life: 250 → 125

So number of half life times is 3. On putting values we get,

T = (8)³

T = 512 days

Hence total duration of time is 512 days.

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