what do you have to do before you preform your experiment?

a. the experiment
b. analyze data
c. form hypothesis

Answer:

Absorbed during the above reaction.

Explanation:

It is lowering the temperature of the reaction mixture, and thus the reaction flask feels cold.

Answer:

Endothermic reaction: absorbs heat from its surroundings.

Explanation:

"Endo" means inside.  "Thermic" refers to heat.

Answer:

1. Find the molar mass of NO2 (46.01)

2. Find the number of moles in 25 g of NO2 (by dividing 25 by the molar mass)     25/46.01 = .54

3. For every 3 moles of NO2 there are 2 moles of HNO3. multiply the number of moles of NO2 by 2/3

.54 x 2/3 = .36

4. Finally, multiply this number by the molar mass of HNO3 (63.018)

.36 x 63.018 = 22.68 g HNO3

Explanation:

The statement, that describes the mass of HNO₃ can be made from mass of NO₂ is "17.1 gram".

A substance is something to do with mass that takes up space. The mass of a compound is the total amount of atoms present in grams that make up a molecule. The grams is the unit of mass. In order to determine the mass in grams, divide the given mass of the substance value by its molar mass to convert gram into mole.

The mass about one cubic centimeter of distilled water at 4°C would be used to describe the gram as a unit.

Gram to mole conversion factor,

[tex]= grams\;*\;\frac{1\;mol}{grams}[/tex]

The balanced chemical equation comes out to be, 2NO₂ + H₂O → HNO₂ + HNO₃

Using the above equation, the moles of NO₂ can be determined from the given mass,

[tex]= \frac{given\;mass}{molar\;mass}\\= 25.0\;g\;*\;\frac{1\;mol}{46.005\;g} \\= 0.5434\;mol Now, HNO_{3} can be made from 25.0 g of NO2= 0.5434\;mol\;NO2\;*\;\frac{1\;mol\;HNO3}{2\;mol\;NO2}\;*\;\frac{63.01\;g\;HNO3}{1\;mol\;HNO3} \\= 17.119\;g\;HNO3\\=17.1\;g\;HNO3[/tex]

Hence the correct answer is 17.1 gram.

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Answer:

Divide its mass by the volume.

Explanation:

Answer: A certain element exists as three different isotopes. 24.1% of all the isotopes have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu. What is the average atomic mass of this element?

Explanation: A certain element exists as three different isotopes. 24.1% of all the isotopes have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu. What is the average atomic mass of this element? 74.92 amu. Use your periodic table to determine which element this is. As. An element exists

The average atomic mass of the element is 74.93 amu

Let the 1st isotope be A

Let the 2nd isotope be B

Let the 3rd isotope be C

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

Abundance of A (A%) = 24.1%

Mass of A = 75.23 amu

Abundance of B (B%) = 48.7%

Mass of B = 74.61 amu

Abundance of C (C%) = 27.2%

Mass of C = 75.23 amu

The average atomic mass of the element can be obtained as follow:

= [(75.23 × 24.1)/100] + [(74.61 × 48.7)/100] + [(75.23 × 27.2)/100]

= 18.13043 + 36.33507 + 20.46256

Thus, the average atomic mass of the element is 74.93 amu

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Answer:

D: dark cloud

E: elliptical galaxy

F: flare star

Answer:

The answer is

Explanation:

The volume of a substance when given the density and mass can be found by using the formula

[tex]volume = \frac{mass}{density} \\[/tex]

From the question

mass = 4500 g

density = 20.5 g/cm³

We have

[tex]volume = \frac{4500 }{20.5} \\ = 219.51219...[/tex]

We have the final answer as

Hope this helps you

Answer:

these are small organism that can not seen by naked eyes

Answer:

D i am prety shure

Explanation:

Answer:-D

Explanation:

Answer:

An objects accelarates in the same direction as that of the force applied.

Explanation:

Answer:

Explanation:

molecular weight of N₂H₄ is as follows

2 x 14 + 4 x 1 = 32

so 32 gram of N₂H₄  is equal to one mole of N₂H₄

25 gram of  N₂H₄ will be equal to 25 / 32 mole of  N₂H₄

so numerical quantity needed to convert grams of  N₂H₄  to mole is

1 / 32 or .03125 . This number needs to be multiplied with grams of N₂H₄

to convert it to number of moles.

Answer:

The answer is molecular mass.

Explanation:

In order to convert grams to moles. you have to find the molar mass of N2H2.

Answer:

Hydrogen, symbol H, has 1 valence electron, Lewis structure is H. Helium, symbol He, has 2 valence electrons, Lewis structure is He: With helium, the first energy level (K shell) is full.

The Lewis dot structure for He has been shown in the image attached.

The general shape of a molecule and the number of bonds an atom can make can both be determined using Lewis structures. They provide a visual representation that aids in understanding chemical bonding and predicting the reactivity and other properties of molecules.

The three-dimensional form of molecules, molecular orbitals, or the presence of lone pairs of electrons are all ignored in Lewis structures, which are simplified models. Making this distinction is essential.

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Answer:

Hydrosphere

Explanation:

Hydrosphere includes all water on the surface of the planet.

Answer:

Hydrosphere

Explanation:

cuz i said so

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\[/tex]

From the question

mass = 10 g

volume = 2 cm³

We have

[tex]density = \frac{10}{5} \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

1.An atom is the smallest constituent unit of ordinary matter that constitutes a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small; typical sizes are around 100 picometers ( 1 × 10−10 m, a ten-millionth of a millimeter, or 1/254,000,000 of an inch).

3.New elements aren't exactly discovered anymore. However, they can be made, using particle accelerators and nuclear reactions. A new element is made by adding a proton (or more than one) to a pre-existing element. This can be done by smashing protons into atoms or by colliding atoms with each other.

4.If an atom gains an electron, it becomes negatively charged.

If an atom loses an electron, it becomes positively charged.

Melting ice cream is a physical change because it is a phase change, the water in the ice cream gains thermal energy and the inter-molecular forces are overcome and the molecules move further apart forming a liquid. It is not a chemical change because no chemical reactions occurred.  

Answer:

chlorine

Explanation:

Because chlorine is in the same period as phosphorus and sodium, but has the most protons in its shell (the most right within the same period) it has the greatest effective nuclear charge.

Explanation:

Carbon-12 (12C) is the more abundant of the two stable isotopes of carbon (carbon-13 being the other), amounting to 98.93% of the element carbon;[1] its abundance is due to the triple-alpha process by which it is created in stars. Carbon-12 is of particular importance in its use as the standard from which atomic masses of all nuclides are measured, thus, its atomic mass is exactly 12 daltons by definition. Carbon-12 is composed of 6 protons, 6 neutrons, and 6 electrons.

Answer:

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

From the question

volume of lead = 27.9 mL

density = 11.34 g/mL

We have

mass = 11.34 × 27.9 = 316.386

We have the final answer as

Hope this helps you

Answer:

1

Explanation:

because you are changing the chemical makeup of the water by pulling out the two chemicals

Answer:

the ability to do something or act in a particular way, especially as a faculty or quality.

Explanation:power, authority, jurisdiction, control, command, sway, dominion mean the right to govern or rule or determine. power implies possession of ability to wield force, authority, or influence. the power to mold public opinion authority implies power for a specific purpose within specified limits.

Answer:

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

From the question

volume = 6 cm³

density = 3.3 g/cm³

We have

mass = 3.3 × 6

We have the final answer as

Hope this helps you

Answer:

C

Explanation:

Answer:

D

Explanation:

Not a because the term exo means outward, so exothermic means releasing energy so D.

Not B or C because they have nothing to do with exothermic (exo- outward thermic- energy)

Answer:

6

Explanation:

All noble gases are nonreactive, these include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).

Answer:

18 elements are nonreactive in the periodic table

Answer:

A

Explanation: