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ehidna [41]
3 years ago
14

Please help me ..If you don't have a question or something to say just comment don't steal my points . It's not fair. Here are t

he questions:

Chemistry
2 answers:
astra-53 [7]3 years ago
3 0

1.

1.20 \: mol \times  \frac{6.02 \times  {10}^{23} }{1 \: mol}  = 7.224 \times  {10}^{23} atoms

2.

9.25 \times  {10}^{25 \:} molecules \times  \frac{1 \: mol}{6.02 \times  {10}^{23} }

= 153.654485 \: moles

3.

molar mass = 3(24.31) + 127.60 + 5(32.07)

molar mass = 360.88 g

4.

molar mass = 3(58.93) + 2(30.97) + 8(16.00)

molar mass = 366.73 g

5.

molar mass = 98.09

125 \: g \times  \frac{1 \: mol}{98.09 \: g}  = 1.274339892 \: moles

//

I'm too lazy to do the rest but you should get a general idea of how to do it.

Also, round as you wish!

madreJ [45]3 years ago
3 0

Ayo, thanks for my points

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Isotopes of the same element will have a different number of neutrons, but the same number of protons. TRUE OR FALSE
Nikitich [7]

Answer:

TRUE

Explanation:

6 0
3 years ago
A 5.000 g mixture contains strontium nitrate and potassium bromide. Excess lead(II) nitrate solution is added to precipitate out
scZoUnD [109]

<u>Answer:</u> The mass percent of potassium bromide in the mixture is 9.996%

<u>Explanation:</u>

  • To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}     .....(1)

<u>For lead (II) bromide:</u>

Given mass of lead (II) bromide = 0.7822 g

Molar mass of lead (II) bromide = 367 g/mol

Putting values in equation 1, we get:

\text{Moles of lead (II) bromide}=\frac{0.7822g}{367g/mol}=0.0021mol

  • The chemical equation for the reaction of lead (II) nitrate and potassium bromide follows:

2KBr+Pb(NO_3)_2\rightarrow PbBr_2+2KNO_3

By Stoichiometry of the reaction:

1 mole of lead (II) bromide is produced from 2 moles of potassium bromide

So, 0.0021 moles of lead (II) bromide will be produced from = \frac{2}{1}\times 0.0021=0.0042mol of potassium bromide

  • Now, calculating the mass of potassium bromide by using equation 1, we get:

Molar mass of KBr = 119 g/mol

Moles of KBr = 0.0042 moles

Putting values in equation 1, we get:

0.0042mol=\frac{\text{Mass of KBr}}{119g/mol}\\\\\text{Mass of KBr}=0.4998g

  • To calculate the percentage composition of KBr in the mixture, we use the equation:

\%\text{ composition of KBr}=\frac{\text{Mass of KBr}}{\text{Mass of mixture}}\times 100

Mass of mixture = 5.000 g

Mass of KBr = 0.4998 g

Putting values in above equation, we get:

\%\text{ composition of KBr}=\frac{0.4998g}{5.000g}\times 100=9.996\%

Hence, the percent by mass of KBr in the mixture is 9.996 %

5 0
3 years ago
Part A Which acid in each of the following pairs has the stronger conjugate base? Match the words in the left column to the appr
vichka [17]

Answer:

HF

H₂S

H₂CO₃

NH₄⁺

Explanation:

<em>Which acid in each of the following pairs has the stronger conjugate base?</em>

According to Bronsted-Lowry acid-base theory, <em>the weaker an acid, the stronger its conjugate acid</em>. Especially for weak acids, pKa gives information about the strength of such acid. <em>The higher the pKa, the weaker the acid.</em>

<em />

  • Of the acids HCl or HF, the one with the stronger conjugate base is HF because it is a weak acid.
  • Of the acids H₂S or HNO₂, the one with the stronger conjugate base is    H₂S  because it is a weaker acid. pKa (H₂S) = 7.04 > pKa (HNO₂) = 3.39
  • Of the acids H₂CO₃ or HClO₄, the one with the stronger conjugate base is H₂CO₃ because it is a weak acid.
  • Of the acids HF or NH₄⁺, the one with the stronger conjugate base is NH₄⁺ because it is a weaker acid. pKa (HF) = 3.17 < pKa (NH₄⁺) = 9.25
6 0
3 years ago
Compare the ability to hold on to / attract electrons between metals and nonmetals.
skad [1K]

Nonmetals have the ability to attract electrons better than metals because they have a higher electron affinity or electronegativity than metals.

<h3>What is electronegativity?</h3>

Electronegativity is the tendency, or a measure of the ability, of an atom or molecule to attract electrons and thus form bonds.

An element in the periodic table with a high electronegativity will automatically have a high electron affinity.

Metals (low electronegativity) are known to lose electrons to non-metals (high electronegativity), hence, nonmetals have the ability to attract electrons better than metals because they have a higher electron affinity or electronegativity than metals.

Learn more about electronegativity at: brainly.com/question/2060520

#SPJ1

5 0
2 years ago
HELP. NO FAKE ANSWERS. I WILL REPORT. I AM CONFUSED AND NEED HELP. FILL IN THE NOT FILLED BOXES POR FAVOR.
SCORPION-xisa [38]
Question #1
Potasium hydroxide (known)
 volume used is 25 ml 
Molarity (concentration) = 0.150 M
Moles of KOH used 
           0.150 × 25/1000 = 0.00375 moles
Sulfuric acid (H2SO4) 
volume used = 15.0 ml
unknown concentration
The equation for the reaction is
2KOH (aq)+ H2SO4(aq) = K2SO4(aq) + 2H2O(l) 
Thus, the Mole ratio of KOH to H2SO4 is 2:1
Therefore, moles of H2SO4 used will be;
      0.00375 × 1/2 = 0.001875 moles
Acid (sulfuric acid)  concentration
    0.001875 moles × 1000/15  
        = 0.125 M

Question #2
Hydrogen bromide (acid)
Volume used = 30 ml
Concentration is 0.250 M
Moles of HBr used;
      0.25 × 30/1000
        =  0.0075 moles 
Sodium Hydroxide (base)
Volume used 20 ml 
Concentration (unknown)
The equation for the reaction is 
NaOH + HBr = NaBr + H2O
The mole ratio of NaOH : HBr   is 1 : 1
Therefore, moles of NaOH used;
                 = 0.0075 moles
NaOH concentration will be 
       = 0.0075 moles × 1000/20
       = 0.375 M

7 0
3 years ago
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