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Bingel [31]
3 years ago
15

How is a mole defined?​

Chemistry
2 answers:
mart [117]3 years ago
7 0

Answer:

The mole is the unit of amount in chemistry. ... A mole of a substance is defined as: The mass of substance containing the same number of fundamental units as there are atoms in exactly 12.000 g of 12C. Fundamental units may be atoms, molecules, or formula units, depending on the substance concerned.

Hope This Helps!  Have A Nice Day!!

sattari [20]3 years ago
6 0

A mole of a substance is defined as: The mass of substance containing the same number of fundamental units as there are atoms in exactly 12.000g of 12C. Fundamental units change depending on the substance.

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What is the volume of 220 grams of an object with a density of 55g/cm square
AnnyKZ [126]
I'm assuming that you meant 55 g/cm^3. Density=\frac{Mass}{Volume}. This is the definition of density. If you rearrange this equation by multiplying each side of the equation by the volume, you get: (Density)(Volume)=Mass. Divide each side by the density to get: Volume=Mass/Density. Now just plug everything in:
V=220 (grams)/55 (grams/cm^3)=<u>4 cm^3</u>
4 0
3 years ago
Electronegativity values increase from left to right across a period in the periodic table because there is an increase in the c
Mademuasel [1]
First, let us define Electronegativity. Electronegativity is "the ability of an atom to attract electrons." In addition, electronegativity increases in elements from left to right, while on the other hand, electronegativity decreases from top to bottom in an element group. It decreases because the atomic radius increases as we go downward an element in the group.
5 0
3 years ago
A chemist prepares a solution of silver nitrate by measuring out of silver nitrate into a volumetric flask and filling the flask
Snezhnost [94]

Amount of silver nitrate taken = 269.μmol AgNO_{3}

Volume of the solution = 300. mL

Concentration of a solution is generally expressed in terms of molarity. Molarity is defined as the moles of a substance present per liter of the solution.

Molarity = \frac{Moles of solute}{Volume of solution(L)}

We want the concentration in millimoles/L.

Converting μmol to millimol solute:

269.μmol * \frac{1 millimol}{1000 micromol} = 0.269 millimol

Volume from mL to L: 300. mL * \frac{1 L}{1000 mL} = 0.300 L

Therefore concentration of the chemist's solution = \frac{0.269 millimol}{0.300 L} =  0.897 \frac{millimol}{L}

8 0
3 years ago
What experiments did Neils Bohr do for the atomic theory?
frozen [14]

Answer(s):

Atomic model

Bohr's greatest contribution to modern physics was the atomic model. The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons.  

Bohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element.

The chemical element bohrium (Bh), No. 107 on the periodic table of elements, is named for him.

Liquid droplet theory

Bohr's theoretical work contributed significantly to scientists' understanding of nuclear fission. According to his liquid droplet theory, a liquid drop provides an accurate representation of an atom's nucleus.

This theory was instrumental in the first attempts to split uranium atoms in the 1930s, an important step in the development of the atomic bomb.

Despite his contributions to the U.S. Atomic Energy Project during World War II, Bohr was an outspoken advocate for the peaceful application of atomic physics.

Quantum theory

Bohr's concept of complementarity, which he wrote about in a number of essays between 1933 and 1962, states that an electron can be viewed in two ways, either as a particle or as a wave, but never both at the same time.

This concept, which forms the basis of early quantum theory, also explains that regardless of how one views an electron, all understanding of its properties must be rooted in empirical measurement. Bohr's theory stresses the point that an experiment's results are deeply affected by the measurement tools used to carry them out.

Bohr's contributions to the study of quantum mechanics are forever memorialized at the Institute for Theoretical Physics at Copenhagen University, which he helped found in 1920 and headed until his death in 1962. It has since been renamed the Niels Bohr Institute in his honor.

Explanation:

Niels Bohr was one of the foremost scientists of modern physics, best known for his substantial contributions to quantum theory and his Nobel Prize-winning research on the structure of atoms.

Born in Copenhagen in 1885 to well-educated parents, Bohr became interested in physics at a young age. He studied the subject throughout his undergraduate and graduate years and earned a doctorate in physics in 1911 from Copenhagen University.

While still a student, Bohr won a contest put on by the Academy of Sciences in Copenhagen for his investigation into the measurements of liquid surface tension using oscillating fluid jets. Working in the laboratory of his father (a renowned physiologist), Bohr conducted several experiments and even made his own glass test tubes.  

Bohr went above and beyond the current theory of liquid surface tension by taking into account the viscosity of the water as well as incorporating finite amplitudes rather than infinitesimal ones. He submitted his essay at the last minute, winning first place and a gold medal. He improved upon these ideas and sent them to the Royal Society in London, who published them in the journal Philosophical Transactions of the Royal Society in 1908, according to Nobelprize.org.  

His subsequent work became increasingly theoretical. It was while conducting research for his doctoral thesis on the electron theory of metals that Bohr first came across Max Planck's early quantum theory, which described energy as tiny particles, or quanta.

In 1912, Bohr was working for the Nobel laureate J.J. Thompson in England when he was introduced to Ernest Rutherford, whose discovery of the nucleus and development of an atomic model had earned him a Nobel Prize in chemistry in 1908. Under Rutherford's tutelage, Bohr began studying the properties of atoms.

Bohr held a lectureship in physics at Copenhagen University from 1913 to 1914 and went on to hold a similar position at Victoria University in Manchester from 1914 to 1916. He went back to Copenhagen University in 1916 to become a professor of theoretical physics. In 1920, he was appointed the head of the Institute for Theoretical Physics.

Hope this helps, have a nice day/night! :D

If it did help, please mark it as brainliest!

4 0
3 years ago
A certain reaction has an activation energy of 39.5 kJ/mol. As the temperature is increased from 25.0°C to a higher temperature,
riadik2000 [5.3K]

Answer:

Explanation:

We shall apply Arrhenius equation which is given below .

ln\frac{k_2}{k_1} = \frac{E_a}{R} [\frac{1}{T_1} -\frac{1}{T_2} ]

K₂ and K₁ are rate constant at temperature T₂ and T₁ , Ea is activation energy .

Putting the given values

ln\frac{5.9}{1} = \frac{39500}{8.3} [\frac{1}{298} -\frac{1}{T_2} ]

.000373= [\frac{1}{298} -\frac{1}{T_2} ]

T₂ = 335.27 K

= 62.27 °C

4 0
3 years ago
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