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2 years ago

Which atom has 20protons and 18 electrons?!

Chemistry

2 answers:

RUDIKE [14]2 years ago

4 0

Explanation:

The atomic number 20 Is the element calcium (Ca). The electron deficit of 2 indicates that it has a positive charge.

Hope this helps

EleoNora [17]2 years ago

3 0

It should be calcium atom, or Ca^2+

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6. What is the molarity of 175 mL of solution containing 2.18 grams of NazS04-10H2O?

Ymorist [56]

Answer:

$Molarity\,\,of\,\,the\,\,solution\,\,is\,\,S=0.039M$

Explanation:

$W=2.18 g\\M=322g\\V=175mL=0.175L\\\\S=\frac{W}{MV} \\=>S=\frac{2.18}{322*0.175} \\So,S=0.039M$

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3 years ago

In the reaction K2CrO4(aq) + PbCl2(aq) → 2KCl(aq) + PbCrO4(s), how many grams of PbCrO4 will precipitate out from the reaction b

Elodia [21]

The balanced chemical reaction is:

<span>K2CrO4(aq) + PbCl2(aq) → 2KCl(aq) + PbCrO4(s)

We are given the amount of the reactants to be used for the reaction. These amounts will be the starting point of our calculations. </span>

<span>
3.0 M K2CrO4 (.500 L) = 1.5 mol K2CrO4

</span>1.5 mol K2CrO4 (1 mol PbCrO4 / 1 <span>mol K2CrO4</span>) ( 323.2 g/mol)=484.8 grams PbCrO4

Therefore, the best answer from the choices is 480 grams.

7 0

3 years ago

1. Calculate the quantity of glucose needed to prepare (a) 250 mL of a 100 mM of

weeeeeb [17]

Answer:

a. mass of glucose required = 4.50 g

b. mass of glucose required = 0.05 g

c. mass of glucose required = 25g

Explanation:

1a. molar mass of glucose = 180.156 g/mol

volume of solution = 250 mL or 250 mL * 1 L/1000 mL = 0.25 L

concentration of solution = 100 mM or 100mM * 1 M/1000 mM = 0.10 M

amount in moles = mass/ molar mass = concentration * volume

mass in grams = concentration * volume * molar mass

mass = 0.10 * 0.25 * 180.156

mass of glucose required = 4.50 g

b. mass concentration of 0.05 % solution = 0.05 g/100 ml = 0.5 g/L

volume of solution = 100 mL = 0.1 L

mass in grams = mass concentration * volume

mass in grams = 0.5 g/L * 0.1 L

mass of glucose required = 0.05 g

c. mass concentration of solution = 50 mg/ mL = 0.05 g/ 0.001 L = 50 g/L

volume of solution = 500 mL = 0.5 L

mass of solute required = concentration * volume

mass required = 50 g/L * 0.5 L

mass of glucose required = 25g

7 0

3 years ago

Which expression represents the ΔH for a chemical reaction in terms of the potential energy, PE, of its products and reactants?

densk [106]

2 - PE of products-PE of reactants.

You are trying to calculate the energy change that occurred from the start of the reaction (the reactants going in) to the end of the reaction (the products coming out). Therefore if there is more energy at the end, you will get a positive result from subtracting the PE of the reactants, and vice versa.

3 0

4 years ago

You are given the following three half-reactions:(1) Fe³⁺(aq) + e⁻ ⇄ Fe²⁺(aq) (2) Fe²⁺(aq) +2e⁻ ⇄ Fe(s) (3) Fe³⁺(aq) +3e⁻ ⇄ Fe(s

RideAnS [48]

The E°half-cell of the (3) is 0.33 volts .

Given,

(1) Fe3+(aq) +e =Fe2+(aq)

(2) Fe2+(aq) +2e = Fe(s)

(3) Fe3+(aq) +3e = Fe(s)

We know ,

E° half-cell of (1) is 0.77 volts .

E° half cell of ( 2) is -0.44 volts .

By resolving or adding equation 1 and 2 we will get (3) ,

Thus , the value of the E° half cell of (3) is given by ,

E°cell = E° half-cell of (1 ) + E° half-cell of (2 ) = 0.77-0.44 = 0.33 volts

Hence the E° half-cell of ( 3 ) is 0.33 volts .

<h3>What is cell potential? </h3>

It is the difference between the electrode potentials of two half cells.

it also defined as the force which causes the flow of electrons from one electrode to the another and thus results in the flow of current.

Ecell = E( cathode) - E ( anode)

<h3>What is electrode potential ? </h3>

The tendency of the electrode to lose of gain electrons is called as electrode potential.

Learn more about cell potential here :

brainly.com/question/19036092

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4 0

2 years ago

Which atom has 20protons and 18 electrons?!​

Which atom has 20protons and 18 electrons?!