Answer:
A number of other chemists before Mendeleev were investigating patterns in the properties of the elements that were known at the time. The earliest attempt to classify the elements was in 1789, when Antoine Lavoisier grouped the elements based on their properties into gases, non-metals, metals and earths. Several other attempts were made to group elements together over the coming decades. In 1829, Johann Döbereiner recognised triads of elements with chemically similar properties, such as lithium, sodium and potassium, and showed that the properties of the middle element could be predicted from the properties of the other two.
It was not until a more accurate list of the atomic mass of the elements became available at a conference in Karlsruhe, Germany in 1860 that real progress was made towards the discovery of the modern periodic table. This area of the website celebrates the work of many famous scientists whose quest to learn more about the world we live in and the atoms that make up the things around us led to the periodic table as we know it today.
Explanation:
PLZ MARK BRAINLIEST
<span>CHCl3 because there are more than two atoms in this molecule that are different. Hydrogen has a small electron cloud and occupies less space, where Cl has a larger electron cloud and occupies more space, this would make it different than the expected tetrahedron shape.</span>
Answer:
True
Explanation:
Hardness is defined as the ability of a substance to resist being scratched. It can be described using Moh's scale
From the given, we can note that the material with hardness 8 has more resistance to being scratched that a material with hardness 7.
This means that if these two substances came in contact, the more hard substance will scratch the less hard substance.
Hope this helps :)
Question:
Zinc metal is added to hydrochloric acid to generate hydrogen gas and is collected over a liquid whose vapor pressure is the same as pure water at 20.0 degrees C (18 torr). The volume of the mixture is 1.7 L and its total pressure is 0.987 atm. Determine the number of moles of hydrogen gas present in the sample.
A. 0.272 mol
B. 0.04 mol
C. 0.997 mol
D. 0.139 mol
E. 0.0681 mol
Answer:
The correct option is;
E. 0.0681 mol
Explanation:
The equation for the reaction is
Zn + HCl = H₂ + ZnCl₂
Vapor pressure of the liquid = 18 torr = 2399.803 Pa
Total pressure of gas mixture H₂ + liquid vapor = 0.987 atm
= 100007.775 Pa
Therefore, by Avogadro's law, pressure of the hydrogen gas is given by the following equation
Pressure of H₂ = 100007.775 Pa - 2399.803 Pa = 97607.972 Pa
Volume of H₂ = 1.7 L = 0.0017 m³
Temperature = 20 °C = 293.15 K
Therefore,
Therefore, the number of moles of hydrogen gas present in the sample is n ≈ 0.0681 moles.
Answer:i don't rlly get the question but this is what i found on the internet :/
Explanation:
When the temperature is increased, the position of equilibrium moves in the endothermic direction to reduce the temperature. ... This means that as the temperature is increased, the position of equilibrium moves to the left, and the yield of ammonia decreases.