Answer:
1
Explanation:
Oxygen is a pure substance therefore it is only made up of one kind of atom
Answer:
i can help you but it only depends on what your working on ?
Explanation . Claim: How solar cells different from silicon. evidence-The most promising group of these new materials are called hybrid lead halide perovskites, which appear to promise a revolution in the field of solar energy.Pure crystalline silicon is a poor conductor of electricity as it is a semiconductor material at its core.In a solar cell, the layers are positioned next to each other and that way an electric field is created.Crystalline silicon cells are made of silicon atoms connected to one another to form a crystal lattice. This lattice provides an organized structure that makes conversion of light into electricity more efficient.Solar cells are made from silicon boules. These are polycrystalline structures that have the atomic structure of a single crystal. The most commonly used method for the creation of the boule is known as the Czochralski method.
Reasoning: Traditional crystalline solar cells are typically made of silicon. An organic solar cell uses carbon-based materials and organic electronics instead of silicon as a semiconductor to produce electricity from the sun. Organic cells are also sometimes referred to as “plastic solar cells” or “polymer solar cells” hybrid perovskites Libai Huang, assistant professor of chemistry at Purdue, says the new material, called a hybrid perovskites, would create solar cells thinner than conventional silicon solar cells, and is also flexible, cheap and easy to make.
<u>Answer:</u> The enthalpy of the overall chemical equation is -205.7 kJ
<u>Explanation:</u>
Hess's law is defined as the law which states that the total amount of heat absorbed or released for a given chemical reaction will remain the same whether the process occurs in one step or several steps.
In this law, a chemical equation is treated as an ordinary algebraic expression that can be added or subtracted to yield the required overall equation.
The enthalpy change or heat of the overall reaction is the summation of the enthalpies or heats of the intermediate reactions involved in the process.
The given overall chemical equation follows:
The intermediate equations for the above reaction are:
(1) 
(2) 
(3) 
According to Hess law, the enthalpy of the reaction becomes:
![\Delta H^o_{rxn}=[1\times (\Delta H_1)] + [1\times (-\Delta H_2)] + [2\times (\Delta H_3)]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B1%5Ctimes%20%28%5CDelta%20H_1%29%5D%20%2B%20%5B1%5Ctimes%20%28-%5CDelta%20H_2%29%5D%20%2B%20%5B2%5Ctimes%20%28%5CDelta%20H_3%29%5D)
Putting values in above expression, we get:
![\Delta H^o_{rxn}=[1\times (74.6)] + [1\times (-95.7)] + [2\times (-92.3)]\\\\\Delta H^o_{rxn}=-205.7kJ](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B1%5Ctimes%20%2874.6%29%5D%20%2B%20%5B1%5Ctimes%20%28-95.7%29%5D%20%2B%20%5B2%5Ctimes%20%28-92.3%29%5D%5C%5C%5C%5C%5CDelta%20H%5Eo_%7Brxn%7D%3D-205.7kJ)
Hence, the enthalpy of the overall chemical equation is -205.7 kJ
Answer/Explanation:
62.559%
mass of an element X 100%
mass of the compound
Scientific Notation: 3.45 x 10^5
E Notation: 3.45e5
A. magnesium sulfate heptahydrate
that is what it stands for
