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Mars2501 [29]
3 years ago
8

13. How many moles of zinc are in 25.00 g Zn?

Chemistry
1 answer:
topjm [15]3 years ago
4 0
0.3824 moles of Zinc
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Stone tools enabled people to hunt and grow crops made the food supply more
Nastasia [14]
It makes it more accessible to everybody
3 0
3 years ago
What is the name of the gas produced when nitric acid is added to copper metal? please help! much appreciated!
Lemur [1.5K]
The answer to your question is nitrogen dioxide

8 0
3 years ago
Sulfuric acid (H2SO4) has a molar mass of 98.1 g/mol. How many oxygen atoms are found in 75.0 g of H2SO4?
nekit [7.7K]

Answer:

18.33 ×10²³ atoms

Explanation:

Given data:

Molar mass of sulfuric acid = 98.1 g/mol

Mass of sulfuric acid = 75.0 g

Number of of oxygen atom present = ?

Solution:

Number of moles of sulfuric acid:

Number of moles = mass/molar mass

Number of moles = 75.0 g/ 98.1 g/mol

Number of moles =0.761 mol

one mole of  sulfuric acid  contain four mole of oxygen atom.

0.761 mol × 4 = 3.044 mol

1 mole = 6.022×10²³ atoms of oxygen

3.044 mol ×  6.022×10²³ atoms of oxygen / 1mol

18.33 ×10²³ atoms

3 0
3 years ago
what mass of sodium fluoride (FW=42.0 g/mol) must be added to 3.50 x 10^2 mL of water to give a solution with pH = 8.40?
MaRussiya [10]

Answer:

Explanation:

Sodium fluoride, being a salt, dissolves in water completely producing F ⁻ ions. Now  F⁻ is the conjugate base of the weak acid HF, so in water we will have the following equilibrium:

F⁻  +  H₂O ⇆ HF + OH⁻

Given this equilibrium, we need to calculate Kb from the Ka for HF,  the [ OH ⁻] from the given pH, and finally the mass needed to produce that  OH⁻ concentration.  

The equilibrium constant, Kb , can be calculated from Kw = Ka x Kb, where Kw = 10⁻¹⁴ and Ka for HF is  6.6 x 10⁻⁴ from reference tables.

Kb = 10⁻¹⁴ / 6.6 x 10⁻⁴ = 1.5 x 10⁻¹¹

pH + pOH = 14  ⇒ pOH = 14 - 8.40 = 5.60

[ OH⁻ ] = 10^-5.60 = 2.51 x 10⁻⁶

Now we have all the information :

                                   F⁻                    HF                        OH⁻

Equilibrium                 X                  2.51 x 10⁻⁶            2.51 x 10⁻⁶

(2.51 x 10⁻⁶)² / X  =  1.5 x 10⁻¹¹     ⇒  X =  (2.51 x 10⁻⁶)²  / 1.5 x 10⁻¹¹

X = [ F⁻ ] = 0.41 M

For 350 mL ( 0.35 L ) we need to add:

0.41 mol HF/ 1 L  *  0.35 L = 0.144 mol

and finally the mass will be:

0.144 mol NaF *  42.0 g/mol NaF = 6.03 g NaF

7 0
3 years ago
(02.01 MC)
inna [77]

It is likely the neutral atom has 6 protons and 6 electrons; while the negatively charged atom has 7 or more electrons.

The mass of an atom, commonly known as the atomic mass is determined by the number of protons and neutrons as electrons have a very low mass.

This means two atoms can have the same number of protons and neutrons, but a different number of electrons, which would make the atom be charged negatively or positively.

Based on this, if there are two atoms, each with 6 protons but one of these is negatively charged it is because the second atom has 1 or more extra.

Neutral atom:

  • This atom has 6 protons and an unknown number of neutrons located in the nucleus.
  • This atom has 6 electrons that orbit the nucleus.
  • The first energetic level will include 2 electrons while the second energetic level will include the 4 remaining electrons.

Negatively-charged atom:

  • This atom has 6 protons and an unknown number of neutrons located in the nucleus.
  • This atom has 7 or even more electrons that orbit the nucleus.
  • The first energetic level will include 2 electrons while the second energetic level will include up to 8 electrons.

Learn more about atoms in: brainly.com/question/13981855

8 0
2 years ago
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