Answer:
New experimental methods
Technological inventions
Explanation:
A scientific theory is usually not based on speculation. Scientific theories must have a solid empirical basis.
However, experimental methods are limited to the caliber of equipments available at the time in which a theory is formulated. With advancing years, more technological sophistication leads to the invention of new instruments and ultimately, the development of new experimental methods.
These innovations are likely to alter existing scientific theories as new evidences emerge, hence the answer.
0.66 M is the accurate molarity of the new solution of volume of 1200 ml.
Explanation:
Data given:
molarity of copper(II) sulphate, Mconc.= 2M
volume of 2M solution taken Vconc. = 400 ml
volume taken for dilution, Vdilute = 1200 ml
molarity of the diluted solution, Mdilute =?
We will use the formula for dilution as
Mconc Vconc = Mdilute x V dilute (conc is concentrated)
putting the values in the equation:
2 x 400 = Mdilute x 1200
Mdilute = 
Mdilute = 0.66 M
When the solution is diluted to the volume of 1200 ml its molarity changes to 0.66 M.
Answer:
When halogen elements react with group one metals they form halide salts.
Explanation:
The elements of group 17 are called halogens. These are six elements Fluorine, Chlorine, Bromine, Iodine, Astatine. Halogens are very reactive these elements can not be found free in nature. Their chemical properties are resemble greatly with each other. As we move down the group in periodic table size of halogens increases that's way fluorine is smaller in size as compared to other halogens elements. Their boiling points also increases down the group which changes their physical states. i.e fluorine is gas while iodine is solid.
When halogen elements react with group one metals they form halide salts.
Alkali metals have one valance electron and halogens needed one electron to complete the octet thus alkali metals loses one electron which is accepted by halogens atom and form ionic compound called halide salts.
For example:
2Na + Cl₂ → 2NaCl
2K + Cl₂ → 2KCl
2Rb + Cl₂ → 2RbCl
2Li + Cl₂ → 2LiCl
With bromine:
2Na + Br₂ → 2NaBr
2K + Br₂ → 2KBr
2Rb + Br₂ → 2RbBr
2Li + Br₂ → 2LiBr
With iodine:
2Na + I₂ → 2NaI
2K + I₂ → 2KBI
2Rb + I₂ → 2RbI
2Li + I₂ → 2LiI
Answer:
84.11 g/mol
Explanation:
A metal from group 2A will form the cation M²⁺, and the ion carbonate is CO₃²⁻, so the metal carbonate must be: MCO₃, and the reaction:
MCO₃(s) → MO(s) + CO₂(g)
For the stoichiometry of the reaction, 1 mol of MCO₃(s) will produce 1 mol of CO₂. Using the ideal gas law, it's possible to calculate the number of moles of CO₂:
PV = nRT , where P is the pressure, V is the volume(0.285 L), R is the gas constant (62.36 mmHg*L/mol*K), n is the number of moles, and T is the temperature (25 + 273 = 298 K).
69.8*0.285 = n*62.36*298
18583.28n = 19.893
n = 0.00107 mol
So, the number of moles of the metal carbonate is 0.00107. The molar mass is the mass divided by the number of moles:
0.0900/0.00107 = 84.11 g/mol
