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2 years ago

Use the portion of the periodic table shown below to answer the questions.

Chemistry

1 answer:

Bingel [31]2 years ago

4 0

The two elements that have the same properties as sodium are potassium and rubidium .

<h3>What is periodic table?</h3>

The periodic table is an arrangement of the elements in order of increasing atomic number.

From the list, the two elements that have the same properties as sodium are potassium and rubidium .

Proton has an atomic number of 20 and a mass number of 40. The number of electrons is the same as the number of protons. Given that the atomic number is the number of protons present, we have 20 electrons and 20 protons.

Number of neutrons = Mass number - Number of protons

= 40 - 20 = 20 neutrons

Learn more about periodic table:brainly.com/question/11155928

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The bottom number on each element of a on the periodic table is called

ruslelena [56]

Answer:

On the periodic table, there are two numbers for every element: the atomic number and the atomic weight.

The numbers at the top of the square represents the number of protons present in the atom's nucleus of that element. This is called the atomic number.

For example, the atomic number for the element Krypton is 36. That means that there are 36 protons in the nucleus. If there were not 36 protons in the nucleus of that atom, that would create the atom of a completely different element. For example, if one proton was to be removed from the nucleus of the atom for the element of Krypton that atom will be an atom of the element bromine.

Explanation:

5 0

3 years ago

what is the approximate ph at the equivalence point of a weak acid-strong base titration if 25 ml of aqueous formic acid require

vivado [14]

Answer:

pH at equivalence point is 8.52

Explanation:

$HCOOH+NaOH\rightarrow HCOO^{-}Na^{+}+H_{2}O$

1 mol of HCOOH reacts with 1 mol of NaOH to produce 1 mol of $HCOO^{-}$

So, moles of NaOH used to reach equivalence point equal to number of moles $HCOO^{-}$ produced at equivalence point.

As density of water is 1g/mL, therefore molarity is equal to molality of an aqueous solution.

So, moles of $HCOO^{-}$ produced = $\frac{29.80\times 0.3567}{1000}moles=0.01063moles$

Total volume of solution at equivalence point = (25+29.80) mL = 54.80 mL

So, at equivalence point concentration of $HCOO^{-}$ = $\frac{0.01063\times 1000}{54.80}M=0.1940M$

At equivalence point, pH depends upon hydrolysis of $HCOO^{-}$ . So, we have to construct an ICE table.

$HCOO^{-}+H_{2}O\rightleftharpoons HCOOH+OH^{-}$

I: 0.1940 0 0

C: -x +x +x

E: 0.1940-x x x

So, $\frac{[HCOOH][OH^{-}]}{[HCOO^{-}]}=K_{b}(HCOO^{-})=\frac{10^{-14}}{Ka(HCOOH)}$

species inside third bracket represent equilibrium concentrations

So, $\frac{x^{2}}{0.1940-x}=5.56\times 10^{-11}$

or, $x^{2}+(5.56\times 10^{-11}\times x)-(1.079\times 10^{-11})=0$

So, $x=\frac{-(5.56\times 10^{-11})+\sqrt{(5.56\times 10^{-11})^{2}+(4\times 1.079\times 10^{-11})}}{2}$

So, $x=3.285\times 10^{-6}M$

So, $pH=14-pOH=14+log[OH^{-}]=14+logx=14+log(3.285\times 10^{-6})=8.52$

5 0

3 years ago

A sample of helium gas has a volume of 2.0 L at a pressure of 4.0 atm. What is the volume of gas at 380 mmHg

Lilit [14]

From equation;
P1V1=P2V2
V2=P1V1÷P2
since P2=380mmHg
now;1atm=760mmHg
how about 380mmHg is equal to how many atm?
380×1÷760=0.5atm
P2 now is equal to 0.5atm
back from equation;
P1V1=P2V2
V2=P1V1÷P2
V2=4.0atm×2.0L÷0.5atm
V2=16L
therefore V2=16L.

5 0

3 years ago

Which of this is the method by which fire extinguisher works?

Andrew [12]

Answer:

the answer is a.cut off the supply of oxygen

8 0

3 years ago

Read 2 more answers

How many moles are in 4.233X 10^21

krek1111 [17]

0.00702906176 moles
hope this helps :)

6 0

3 years ago