Answer:
1) 0.0625 g.
2) 0.0125 g.
Explanation:
<em>1) A solution of NaOH has a concentration of 25.00% by mass. What mass of NaOH is present in 0.250 g of this solution?</em>
mass% of NaOH = [(mass of NaOH)/(mass of solution)] x 100.
mass% of NaOH = 25.0%, mass of NaOH = ??? g, mass of solution = 0.250 g.
∴ mass of NaOH = (mass% of NaOH)(mass of solution)/100 = (25.0%)(0.250 g)/100 = 0.0625 g.
<em>2) What mass of NaOH must be added to the solution to increase the concentration to 30.00% by mass?</em>
We can use the relation:
mass% of NaOH = [(mass of NaOH)/(mass of solution)] x 100.
mass% of NaOH = 30.0%, mass of NaOH = ??? g, mass of solution = 0.250 g.
∴ mass of NaOH = (mass% of NaOH)(mass of solution)/100 = (30.0%)(0.250 g)/100 = 0.075 g.
∴ The mass of NaOH should be added = 0.075 - 0.0625 = 0.0125 g.
Acid is a kind of chemical compound that when dissolved in water gives a solution with H+ ion activity more than purified water. A base is an aqueous substance that donates electrons, accept protons or release hydroxide (OH-) ions. An acid is a proton donor. While a base is a proton acceptor.
<u>Answer:</u> The group of elements that corresponds to the electronic configuration is group 13.
<u>Explanation:</u>
Electronic configuration is defined as the representation of electrons in a given atom.
Valence electrons are defined as the electrons present in the outermost shell or the sub-shell having highest value of 'n'.
We are given:
General electronic configuration =
where,
n = principal quantum number and is determines the energy level of the sub-shell
The number of valence electrons in the configuration are = 2 + 1 = 3
And, as the last electron is entering the p-subshell, so the element is a p-block element.
The given electronic configuration is of group 13 elements.
Hence, the group of elements that corresponds to the electronic configuration is group 13.
Answer:
0.66g of water
Explanation:
Molar heat of vaporization of any substance is defined as the heat necessary to vaporize 1 mole of the substance.
If heat of vaporization of water is 40.79kJ/mol and you add 1.50kJ, the moles you vaporize are:
1.50kJ × (1mol / 40.79kJ) = 0.0368 moles of water.
As molar mass of water is 18.01g/mol, mass of water that can be vaporized are:
0.0368 moles × (18.01g / mol) = <em>0.66g of water</em>
I think B or D because an eye obviously doesn't have a lense, mirror..maybe sorry for not giving u straight forward response