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3 years ago

Magnesium and calcium have similar chemical properties because their atoms in the ground state have

Chemistry

2 answers:

stiv31 [10]3 years ago

4 0

Answer:

The answer is 4

Explanation:

Since magnesium and calcium have the same number of valence electrons, and since the valence electrons are located in the outermost shell so the reasonable is 4

zhenek [66]3 years ago

3 0

Answer:

4- two electrons in the outermost shell

Explanation:

Magnesium and Calcium both have 2 electrons in their valence/outermost shell. Chemical properties of an element is determined by the configuration of its electrons in orbits around nucleus. Since the number of protons and electrons are the same it essentially means atomic number determines the chemical behavior of an element so that is why Mg and Ca have same chemical properties.

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Where the oxygen comes from the air (21% O2 and 79% N2). If oxygen is fed from air in excess of the stoichiometric amount requir

guajiro [1.7K]

Answer:

$y_{O2} =4.3$ %

Explanation:

The ethanol combustion reaction is:

$C_{2}H_{5} OH+3O_{2}$ → $2CO_{2}+3H_{2}O$

If we had the amount (x moles) of ethanol, we would calculate the oxygen moles required:

$x*1.10(excess)*\frac{3 O_{2}moles }{etOHmole}$

Dividing the previous equation by x:

$1.10(excess)*\frac{3 O_{2}moles}{etOHmole}=3.30\frac{O_{2}moles}{etOHmole}$

We would need 3.30 oxygen moles per ethanol mole.

Then we apply the composition relation between O2 and N2 in the feed air:

$3.30(O_{2} moles)*\frac{0.79(N_{2} moles)}{0.21(O_{2} moles)}=121.414 (N_{2} moles )$

Then calculate the oxygen moles number leaving the reactor, considering that 0.85 ethanol moles react and the stoichiometry of the reaction:

$3.30(O_{2} moles)-0.85(etOHmoles)*\frac{3(O_{2} moles)}{1(etOHmoles)} =0.75O_{2} moles$

Calculate the number of moles of CO2 and water considering the same:

$0.85(etOHmoles)*\frac{3(H_{2}Omoles)}{1(etOHmoles)}=2.55(H_{2}Omoles)$

$0.85(etOHmoles)*\frac{2(CO_{2}moles)}{1(etOHmoles)}=1.7(CO_{2}moles)$

The total number of moles at the reactor output would be:

$N=1.7(CO2)+12.414(N2)+2.55(H2O)+0.75(O2)\\ N=17.414(Dry-air-moles)$

So, the oxygen mole fraction would be:

$y_{O_{2}}=\frac{0.75}{17.414}=0.0430=4.3$ %

6 0

3 years ago

The rate constant for this second‑order reaction is

o-na [289]

Answer:

daddadaddddddddddddddddddddddddddddda

Explanation:

dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd

3 0

3 years ago

It is found when an unknown solid solute is dissolved in water that the solubility of the solid increases if temperature is decr

mina [271]

Answer:

exothermic entropy is increased

Explanation:

An exothermic process is one whose rate increases when the temperature is decreased. Hence if a decrease in temperature favours the dissolution of more solute at equilibrium, then the process is exothermic.

Similarly, the dissolution of a solute in a solvent increases the disorderliness (entropy) of the system because of the increase in the number of particles present. Hence once a solute in dissolved, the entropy of the system increases.

5 0

3 years ago

Science quiz help plssssss

xxMikexx [17]

Answer:

3. It should restate the question

4. a controlled experiment

5. if I freeze a tennis ball then it will not bounce as high

Explanation:

6 0

2 years ago

Which element is placed in the same period as ruthenium but has a higher atomic number than it

Blababa [14]

Since it is in period five, any element that has a higher atomic number than it could be an answer, therefore, silver, bismuth, and osmium are possibilities.

8 0

3 years ago

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