A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.
For example, if a piece of paper is cut up into small pieces it still is paper. This would be a physical change in the shape and size of the paper. If the same piece of paper is burned, it is broken up into different substances that are not paper.
When heat is given off in a chemical change or reaction, it is called an exothermic reaction. When heat is absorbed in a chemical change or reaction, it is called an endothermic reaction. The speed at which chemical reactions take place depend on the temperature pressure and how concentrated the substances involved in the chemical reaction are. Sometimes substances called catalysts are used to speed up or help along a chemical reaction. Light is helpful in the processing of film.
57.13% is the mass percent of oxygen in sodium bicarbonate. Mass percentage, also known as weight percentage or mass percent.
Mass percentage, also known as weight percentage, is a way of expressing the concentration of a component in a mixture or a compound. It represents the mass of the component (usually expressed in grams) per 100 grams of the mixture or compound. Mass percentage is commonly used in chemistry and other scientific fields to quantify the amount of a particular substance relative to the total mass of the mixture.
Na = 22.99 g/mol
H = 1.00 g/mol
C = 12.01 g/mol
O = 15.99 g/mol
Molar Mass of solution = (22.99 g/mol) + (1.00 g/mol) + (12.01 g/mol) + (15.99 g/mol x 3)
= 83.97 g/mol
(47.97 g/mol) / (83.97 g/mol) x 100 = 57.13%
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Answer:
Molar mass of NaHCO3 = 84.00661 g/mo
Explanation:
This compound is also known as Baking Soda or Sodium Bicarbonate.
Convert grams NaHCO3 to moles or moles NaHCO3 to grams
Molecular weight calculation:
22.98977 + 1.00794 + 12.0107 + 15.9994*3
A. Heat does not transfer between his body and the water
B. Heat transfers to his body from the water by conduction
C. Heat transfers from his body to the water by convection
D. Heat transfers from his body to the water by conduction
Thank you !
Answer is: B. Heat transfers to his body from the water by conduction.
Thermal conductuction is the transfer of heat through physical contact. Thermal conduction is the transfer of heat by microscopic collisions of particles.
Heat spontaneously flows from a hotter (in this example water) to a colder body (in this example human body).
The process of heat conduction depends on four basic factors: the temperature gradient, the cross section of the materials involved, their path length and the properties of those materials.
(2) CaCl2 (4) NiCl2
Answer:
Iron can not form iron(i) selenide however it can form iron(ii) selenide.
Explanation:
The possible oxidation states of iron are +2 and +3.
Iron can form iron (ii) selenide.
The formula of iron (ii) selenide is FeSe.
In iron (ii) selenide the oxidation state of iron is +2.
The ratio of both atoms are 1:1.
Its molecular weight is 134.82 g/mol.
It is toxic compound.
Its melting point is 965°C.
Its density is 4.72 g/cm³.
Iron can also form iron (iii) selenide.
The formula of iron (iii) selenide is Fe₂Se₃.
In iron (iii) selenide the oxidation state of iron is +3.
The ration of both atoms are 2:3.
It also known as ferric selenide.
Its molecular weight is 348.57 g/mol.
Answer:
The radioactive dating method is one of the efficiently used methods in order to calculate the age of the rocks, meteorites, fossils and various other objects, depending upon the rate at which radioactive isotopes decay. In this method, an unstable element changes into a stable one, releasing some amount of radiation and losing a certain amount of energy.
This is efficient in determining the age of the earth. The earth is comprised of rocks that are present from the time of its formation. These rocks can be dated using this method and the approximate age of the rock is evaluated.
The Uranium-Lead dating (²³⁸U-²⁰⁶Pb) method was used to date the smaller zircon crystals of Australia that are about 4.4 billion years old. The half-life of U-238 is approximately 4.5 billion years, which shows that these are one of the oldest rocks on earth and helps in understanding how old the earth is.
Half-life is defined as the time required by a radioactive isotope to decay half of its atoms.
So the radioactive dating method is one of the common method gives the approximate age of the earth.
Answer:
So, we rely on radiometric dating to calculate their ages. Radiometric dating, or radioactive dating as it is sometimes called, is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes.
Explanation:
radiometric dating is a very accurate way to date the Earth.We know it is accurate because radiometric dating is based on the radioactive decay of unstable isotopes. When an unstable Uranium (U) isotope decays, it turns into an isotope of the element Lead (Pb).