A cup of coffee contains 500 mg of caffeine which has the chemical formula C8H10N4O2. Which one of the following is the number of nitrogen atoms present in this amount of caffeine?
A 1.55x10^21
B 6.21x10^21
C 1.55x10^23
D 6.21x10^24

the answer is B but i dont know the method!

Answers

Answer 1

Answer:

= 6.21x10^21

Explanation:

It's the train track method, where you try to cancel all the units and end with units that you need. Here we want to end with number of atoms of N.

500 mg N x 1 g N/1000 mg N x 1 mol N/194.19 g N x 4 mol N/1 mol of caffeine x (6.022 x 10^23 particles of N / 1 mol N)

= 6.21x10^21


Related Questions


Which of the following are examples of useful hydrocarbons?

Answers

Answer:

the most useful hydrocarbon is fuel.

Explanation:

some examples like: natural gases,coal,diesel fuel, kerosene etc.

The most useful hydrocarbon is fuel like gasoline, natural gas, fuel oil, diesel, jet fuel, coal, kerosene, and propane.

What are hydrocarbons ?

The term hydrocarbon is defined as the compound which is made up of hydrogen and carbon. They are useful as energy sources. Hydrocarbons are examples of group 14 hydrides.

There are four types of hydrocarbon that are alkanes, alkenes, alkynes and aromatic hydrocarbons.

Among the most widely used hydrocarbon fuels include gasoline, natural gas, fuel oil, diesel, jet fuel, coal, kerosene, and propane. Plastics and synthetic fabrics like polyester are made using hydrocarbons as well.

Thus, The most useful hydrocarbon is fuel like gasoline, natural gas, fuel oil, diesel, jet fuel, coal, kerosene, and propane.

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If the difference in electronegativity between atoms of differnt non-metals is small, the atoms of the two non-
metals will most likely-

Answers

Answer:

Form  covalent bond

Explanation:

If their electronegativity is same or very close they will likely form covalent bond (where they share electrons)


How many mL of 2.52 Macid does it take to titrate 1,527mL of 5.09 M base?

Answers

[tex]thanks \: for \: points[/tex]

brainliestmark me as

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How can glass be a liquid if it's so hard?​

Answers

Answer:

It is an amorphous solid and hence also called pseudo solid. So it flows very slowly over thousands of years. It is not visible to the n*ked eye.

Which organisms are consumers?

Choose all correct answers.


Mushrooms

Snake

Frog

Grasshopper

Monkey

Grass

Answers

Answer:

Snake

Frog

Grasshopper

Monkey

Mushroom

when water becomes tasty it is called?

Answers

Answer:

sour ??

Explanation:

Our tongues have a way to detect water. They do it not by tasting the water itself, but by sensing acid — which we usually call sour.

A calorimeter holds 50 g water at 22.0°C. A sample of hot iron is added to the water. The final temperature of the water and iron is 28.0°C. What is the change in enthalpy associated with the change in the water’s temperature?
Note: The specific heat of water is 4.18 J/°C

Use the formula ΔH = - cmΔT

Answers

The change in enthalpy associated with the change in the water’s temperature is 1254 J.

What is specific heat?

The amount of heat required to increase the temperature of one gram of a substance by one Celsius degree is known as specific heat.

Enthalpy change will be calculated as:

ΔH = -cmΔT, where

m = mass of water = 50g

c = specific heat of water = 4.18J/g°C

ΔT = change in temperature = 28 - 22 = 6 °C

On putting values in the above equation, we get

ΔH = -(4.18)(50)(6) = -1254 J

Hence change in enthalpy of the reaction is -1254 J.

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are sedimentary rocks formed weathering erosion and deposition?

Answers

Answer:

yes

Explanation:

sedimentary rocks are mad from erosion and weathering!

weathering erosion and deposition occur to form every sedimentary rock that exist on Earth weathering is the creation of sediment through its supposed to wind or water tearing off pieces or do I survive a logical activity such as tree roots and animal hooves breaking at rock erosion is the transportation of the sediments from origin to deposition through wind water or glacial ice deposition is the process of the sediments being dropped off by their mode of movement or erosion method by glacial ice when are water.

Solve 21 and 22 please

Answers

Answer:

try youre best to succsess

Which experiment led to the idea that atoms contained a nucleus?
O A. Niels Bohr's photoelectric effect experiment
O B. Ernest Rutherford's gold foil experiment
O C. J. J. Thomson's cathode ray experiment
O D. Robert Millikan's oil drop experiment

Answers

Answer:

B. Ernest Rutherford's gold foil experiment

Explanation:

That experiment showed a space with the tiny dense spot, referred to as the nucleus. The experiment involved shooting alpha particles (helium nuclei) at a very thin sheet of gold and then observing.

What volume is occupied by a 0.118 mol of helium gas at a pressure of 0.97 atm and a temperature of 305 K ? Would the volume be different if the gas was argon (under the same conditions) ?

Answers

Answer:

See below

Explanation:

PV = n RT        R = .082057  L - Atm / (K-Mole)

.97 V = .118 (.082057)(305)    

    V = 3.04 liters

Will not change for argon.....will be the same for all ideal gases

I) Choose The Correct Answer 1. Which of the following statement correctly describes the law of conservation of mass? A/ It states that the total mass of reactants is equals with the total mass of products in all chemical reaction B/ The total numbers of atoms at the left should be equal with the total numbers of atoms at the right side of arrow C/Atom is neither created nor destroyed in any chemical reaction D/ All E/ None​

Answers

Answer:

D all

Explanation:

because law of conservation of mass describes A, B and C statement

What is the concentration of OH- of a solution with an H3O+ concentration equal to 6.31 E-7 M?

Answers

[OH⁻] = 0.158 x 10 ⁻⁷ M is the concentration of OH- of a solution with an H3O⁺ concentration equal to 6.31  x 10 ⁻⁷ M.

What is pH scale ?

The letters pH stand for the power of the hydrogen ion. The pH of a solution is the negative logarithm of the hydrogen-ion concentration.

pH = - [log H⁺]

[tex]\rm [H^{+}] [OH^{-}] = 1 \times 10^{-14}[/tex]

[tex]\rm[OH^{-}] = \dfrac{1 \times 10^{-14} }{ [H^{+}] }[/tex]

[tex]\rm[OH^{-}] = \dfrac{1 \times 10^{-14} }{ 6.31 \times 10^{-7} }[/tex]

[OH⁻] = 0.158 x 10 ⁻⁷ M

Therefore [OH⁻] = 0.158 x 10 ⁻⁷ M is the concentration of OH- of a solution with an H3O+ concentration equal to 6.31  x 10 ⁻⁷ M.

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What strand of mRNA would be produced from the strand of DNA shown
below?
GCT AAG
• A. GCA UUG

B. CGA TTC
C. CGA UUC
• D. GCT AAG

Answers

I think C would be the right choice

CGA UUC are the strands of mRNA that would be produced from the strand of DNA shown. Therefore, the correct option is option C.

What is DNA?

Deoxyribonucleic acid, or DNA, is an organic molecule with a complex molecular structure which is present in all cells, both prokaryotic and eukaryotic, as well as in a variety of viruses. For the transfer of inherited traits, DNA codes genetic information. The discovery significantly improved scientists' knowledge of DNA replication including the genetic regulation of biological processes.

Despite the fact that the molecule DNA was initially identified in 1869, its significance for the transmission of genes was not demonstrated till 1943. James Watson with Francis Crick discovered that the molecular makeup of DNA consists of a double-helix polymers, a spiral made up of two DNA strands twisted around one another, in 1953 with the help of biophysicists Rosa Lind Franklin with Maurice Wilkins. CGA UUC are the strands of mRNA that would be produced from the strand of DNA shown.

Therefore, the correct option is option C.

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Why does the shape of the moon appear to change over the course of about a month? (2 points)

Group of answer choices

The sun is always lighting up the same amount of the moon.

The sun is lighting up different amounts of the moon.

The moon changes sh

Answers

Answer:

The sun is lighting up different amounts of the moon.

Explanation:

Magnesuim Bromide is a (an) _____ compound.

Answers

Answer:What type of compound is Magnesium bromide?

Magnesium bromide (MgBr2) is a chemical compound of magnesium and bromine that is white and deliquescent. It is often used as a mild sedative and as an anticonvulsant for treatment of nervous disorders. It is water-soluble and somewhat soluble in alcohol.

Explanation:

an ionic compound :)

2. The figure shows the phase transition of water. Use it to answer question:

120°
5
s/
4
100°
80°
60°
3
40°
20°
2

71
-10°
During which period(s) of time is water in the liquid phase?
A 2
B 2 and 3
C 3
D D 3 and 4

Answers

C. 3 because 1 is the solid phase and 2 is where the solid turns to liquid.

What is the meteorology tool that is an area where weather data is collected from various sources to make predictions

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Answer:

Weather maps im sorry im not sure but i think its the answer

A sample of carbon monoxide gas is contained in a 345 mL vessel at a temperature of 25 °C. and a pressure of 985 mm
Hg. The gas is allowed to expand to a new volume of 4.50 liters at constant temperature. What is the new pressure? 1 atm
= 760 mm Hg.

Answers

The new pressure is 75.51 mmHg if a sample of carbon monoxide gas is contained in a 345 mL vessel at a temperature of 25 °C. and a pressure of 985 mmHg and the gas is allowed to expand to a new volume of 4.50 litres at a constant temperature.

What is a gas law?

The gas laws consist of three primary laws: Charles' Law, Boyle's Law and Avogadro's Law (all of which will later combine into the General Gas Equation and Ideal Gas Law).

The pressure on the gas changes, while the temperature remains constant, and we want to find the new volume. So, we will use Boyle's Law, which states there is an inverse relationship between the pressure on a gas and the volume of the gas. The formula is:

[tex]P_1V_1=P_2V_2[/tex]

[tex]P_1 = 985 mm Hg[/tex]

[tex]V_1 = 345 mL[/tex] =

[tex]P_2 = ?[/tex]

[tex]V_2 = 4.50 liters[/tex]

The pressure of the gas is originally 985 mm Hg and the volume is 345 mL.

We are solving for the new volume, so we must isolate the variable V₂.

Now putting all the values in the equation:

[tex]P_1V_1=P_2V_2[/tex]

[tex]985 X 0.345 L=P_2 X 4.50[/tex]

[tex]P_2[/tex] = 75.51 mmHg

Hence, the new pressure is  75.51 mmHg.

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What is pH defined as?

Answers

Answer:

pH is a measure of how acidic/basic water is. The range goes from 0 to 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water.

Explanation:

hope this helps if not let me know have a great day

What mass of copper is used to produce 2.87 moles of copper (II) oxide?

The answer is 182 but I don't know why

Answers

Answer:

182.532 [gr.].

Explanation:

1) equation of this reaction is:

2Cu+O₂⇒2CuO;

2) according to the equation made up above, ν(CuO)=ν(Cu); it means ν(Cu)=2.87 (mol.), then

3) m(Cu)=ν(Cu)*M(Cu);

m(Cu)=2.87*63.6=182.532 [gr].

ITS DUEEE brainliest+15 points place plastic wrap infrony of a flashlight what do you observe? after that place wax paper in front of the flashlight Does the waxed paper affect how the light hits the paper on the wall? Explain your response.

Answers

Plastic wrap is transparent and so nearly all light passes through easily ,

Wax Paper is translucent and so light is blurred or scattered .

What is Reflection ?

Reflection of light occurs when light hits a smooth surface that does not absorb any of the light but instead bounces it back off the surface.

A mirror is flat, smooth, and polished. When light hits a mirror it is not absorbed but is reflected off at a very predictable angle.

The angle that the light hits the mirror is called the angle of incidence.

The angle of light that bounces off the mirror is called the angle of reflection.

The Law of Reflection states that the angle of incidence is equal to the angle of reflection.

Plastic wrap is transparent and so nearly all light passes through easily ,

Wax Paper is translucent and so light is blurred or scattered .

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(50 points) A chemist reacted 15.0 liters of F2 gas with NaCl in the laboratory to form Cl2 and NaF. Use the ideal gas law equation to determine the mass of NaCl that reacted with F2 at 280. K and 1.50 atm.


F2 + 2NaCl → Cl2 + 2NaF


Part 2. Explain how you would determine the mass of sodium chloride that can react with the same volume of fluorine gas at STP.

Answers

A. The mass of NaCl needed to react with F₂ at 280 K and 1.50 atm is 115.83 g

B. The mass of NaCl needed to react with F₂ at STP is 78.39 g

A. How to determine mass of NaCl needed at 280 K and 1.50 atm

We'll begin by calculating the number of mole of F₂ by using the ideal gas equation as follow:

Volume (V) = 15 LTemperature (T) = 280 KPressure (P) = 1.5 atm Gas constant (R) = 0.0821 atm.L/Kmol Number of mole (n) =?  

n = PV / RT

n = (1.5 × 15) / (0.082 × 280)

n = 0.98 mole

Next, we shall determine the number of mole NaCl that reacts. This is given below

F₂ + 2NaCl → Cl₂ + 2NaF

From the balanced equation above,

1 mole of F₂ reacted with 2 moles of NaCl.

Therefore,

0.98 mole of F₂ will react with = 0.98 × 2 = 1.96 moles of NaCl

Finally, we shall determine mass of NaCl as follow

Mole of NaCl = 1.96 molesMolar mass of NaCl = 58.5 g/mol Mass of NaCl =?

Mass = mole × molar mass

Mass of NaCl = 1.98 × 58.5

Mass of NaCl = 115.83 g

B. How to determine mass of NaCl needed at STP

At standard temperature and pressure (STP),

22.4 L = 1 mole of F₂

Therefore,

15 L = 15 / 22.4

15 L = 0.67 mole of F₂

Next, we shall determine the number of mole NaCl that reacts. This is given below

F₂ + 2NaCl → Cl₂ + 2NaF

From the balanced equation above,

1 mole of F₂ reacted with 2 moles of NaCl.

Therefore,

0.67 mole of F₂ will react with = 0.67 × 2 = 1.34 moles of NaCl

Finally, we shall determine mass of NaCl as follow

Mole of NaCl = 1.34 molesMolar mass of NaCl = 58.5 g/mol Mass of NaCl =?

Mass = mole × molar mass

Mass of NaCl = 1.34 × 58.5

Mass of NaCl = 78.39 g

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i need the second question asap please

Answers

Answer:

Running to catch the bus would be it

Explanation:

because you're running for the others you barly move

When will the pain end?

Answers

Answer:

(when you get a girl)

Pain is a sensory trigger from your brain to represent the fact that something —or someone— could be hurting you. The pain will end once the thing causing it stops, as in a cause-effect scenario.

Mental health though, can be helped by finding happiness in life, like getting off of clash of clans and touching grass.

Why do scientists use stirbars in the laboratory?

Answers

Answer:

A stir bar consists of a magnetic bar used to agitate a liquid mixture or solution

Explanation:

Predict the products of each reaction. Balance the equation, and then write the net ionic equation

Answers

A chemical equation is an equation showing the formation of new products from reactants.

What is a chemical reaction?

A chemical reaction is a reaction which involves changes in the composition and chemical properties of substances resulting in the formation of new substances.

A chemical reaction is usually represented by chemical equations.

A balanced chemical equation is one in which the atoms of elements are equal on both sides of the equation.

A net ionic equation shows only the ions that form products.

Therefore, a chemical equation is an equation showing the formation of new products from reactants.

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2.) At what temperature in Celsius will a 1.0g sample of neon gas exert a pressure of 500 torr in a 5.01 L container. (Hint: use the Ideal Gas Law)

Answers

The required temperature of the sample of gas is 823K.

What is ideal gas equation?

Ideal gas equation gives idea about the behavior of gas at different condition & represented as:

PV = nRT, where

P = pressure = 500 torr = 0.657 atmV = volume = 5.01 LR = universal gas constant = 0.082 L.atm / K.molT = temperature = ?n = moles

Moles will be calculated as:
n = W/M, where

W = given massM = molar mass

Moles of Neon gas = 1g / 20.1g/mol = 0.049 mole

On putting all these values in the above equation, we get

T = (0.657)(5.01) / (0.049)(0.082) = 822.8 = 823 K

Hence required temperature of the sample is 823 K.

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8 marks (a) Given the following information: AH = -116 kJ AH = -256 kJ Eqn. 1: Eqn. 2: 2NO(g) + O2(g) 2NO2(g) 2N2(g) + 502(g) + 2H2O(C) ► 4HNO3(aq) N2(g) + O2(g) → 2NO(g) AH = +183 kJ Eqn. 3: Use Hess's Law to calculate the enthalpy change for the reaction below (Show your working) AHrın = ??? 3NO2(g) + H2O(l) → 2HNO3(aq) + NO(g) AHHO​

Answers

Enthalpy change is the heat that evolved or got absorbed in a reaction mixture. The enthalpy change for the reaction is -137 kJ.

What is Hess's law?

Hess's law states that the enthalpy for the whole reaction will be equal to the summation of all changes that are independent of the steps of the reaction.

First, arrange all the reactions and balance them, first the data of equation 1 is rearranged:

NO₂ must be on the reactant side and must be multiplied by 3/2 so that 3 moles of NO are balanced.

3 NO₂ (g) → 3 NO (g) + 3/2 O₂ (g),    ΔH = + 174 kJ

Now, for equation 2: the moles of HNO₃ required is 2 so the whole equation will be divided by 2 as,

N₂ (g) + 5/2 O₂ (g) + H₂O (l) → 2HNO₃ (aq),      Δ H = -128 kJ

Now, for equation 3: N₂ and O₂ should be eliminated and reversed as,

2NO (g) → N₂(g) + O₂(g)    ΔH = -183 kJ

Now, to determine the enthalpy the rearranged equation 1, 2, and 3 are added to get the final equation:

3NO₂ (g) + H₂O (l) → 2HNO₃ (aq) + NO (g)

Δ H = 174 - 128 - 183

= -137 kJ

Therefore, -137 kJ is the enthalpy change.

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What is the equivalent weight of water

Answers

Answer:

Atomic weight of Hydrogen is 1. There are 2 Hydrogen atoms in water molecule. So it is 2. Oxygen atomic weight is 16.0 and adding 2 and 16, we will get 18.18 is the equivalent weight of water.

Explanation:

Hope this helps

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