How many protons are in an isotope of sodium with a mass number of 25? 11
Answer: element.
Justification:
1) A molecule is the union of two or more atoms.
2) When two or more atoms of different elements bond together, the molecule formed is a compound.
For example: one atoms of hydrogen and one atom of chlorine form the molecule HCl, which is a compound (hydrogen chloride).
3) When the molecules is formed by two atoms of the same element, it is not called a compound, but element. Some examples of this are the diatomic gases:
H₂: hydrogen
Cl₂: chlorine
Br₂: bromine
O₂: oxygen
S₂: sulfur
N₂: nitrogen.
Answer:
Explanation:The final homogenous solution, after cooling it to 40°C, will contain 47 g of potassium sulfate disolved in 150 g of water, so you can calculate the amount disolved per 100 g of water in this way:
[47 g of solute / 150 g of water] * 100 g of g of water = 31.33 grams of solute in 100 g of water.
So, when you compare with the solutiblity, 15 g of solute / 100 g of water, you realize that the solution has more solute dissolved with means that it is supersaturated.
To make a saturated solution, 15 grams of potassium sulfate would dissolve in 100 g of water.
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From the equation q=mCΔT, set the q of copper = to q of water,
So --- mCΔT(copper)=mCΔT(water).
mass (Cu - copper) = 38g
mass (H2O - water) = 15g
C (H2O) = 4.184 J/g*C
ΔΤ (H2O) = 33-22 = 11*C
ΔΤ (Cu) = 33-80 = -47*C (the final temp is the same for both materials - thermal equilibrium)
C (Cu) = ?
So --- 38(-47)C[Cu]=15(4.184)(11)
--- C[Cu]=690.36/(-1786) = 0.3865 J/g*C, or 0.39 in 2 sig figs. (The negative goes away, because specific heats are usually positive)
Answer:
Dmitri Mendeleev
Explanation:
Dmitri Mendeleev a Russian Chemist arranged elements on the periodic table according to their atomic mass. He used this arrangement to predict some of the properties of the missing element.
- Dmitri Mendeleev around 1869 described the periodic table.
- The table was based on the periodic law which states that "chemical properties of elements are a periodic function of their atomic weights".
- In the Mendeleev table, elements are arranged by atomic weights with recurring properties in a periodic manner.
