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2 years ago

Hello can u answer these quickly?

Chemistry

1 answer:

mars1129 [50]2 years ago

8 0

Answer:

1. 6electrons because in an a neutral atom, the number of electrons and protons are equal

2. Atomic number is 10

3. 15electrons, Atomic number 15,Mass number 32

4. 7protons, Atomic number 7

1. 15protons,16neutrons

2.Number of protons is 9, atomic number is 9

3.Number of protons is 27, Atomic number is 27

Explanation:

The mass number (A)=Atomic/proton number (Z)+Neutron number (N)

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5. What concentration of acid must be added to change the pH of 1 mM phosphate buffer from 7.4 to 7.3 (pKas of the phosphate buf

mr_godi [17]

Explanation:

According to the Henderson-Hasselbalch equation, the relation between pH and $pK_{a}$ is as follows.

pH = $pK_{a} + log \frac{base}{acid}$

where, pH = 7.4 and $pK_{a}$ = 7.21

As here, we can use the $pK_{a}$ nearest to the desired pH.

So, 7.4 = 7.21 + $log \frac{base}{acid}$

0.19 = $log \frac{base}{acid}$

$\frac{base}{acid}$ = 1.55

1 mM phosphate buffer means $[HPO_{4}]$ + $[H_{2}PO_{4}]$ = 1 mM

Therefore, the two equations will be as follows.

$\frac{HPO_{4}}{H_{2}PO_{4}}$ = 1.55 ............. (1)

$[HPO_{4}]$ + $[H_{2}PO_{4}]$ = 1 mM ........... (2)

Now, putting the value of $[HPO_{4}]$ from equation (1) into equation (2) as follows.

1.55 $[H_{2}PO_{4}] + [tex][H_{2}PO_{4}]$ = 1 mM

2.55 $[H_{2}PO_{4}]$ = 1 mM

$[H_{2}PO_{4}]$ = 0.392 mM

Putting the value of $[H_{2}PO_{4}]$ in equation (1) we get the following.

0.392 mM + $[HPO_{4}]$ = 1 mM

$[HPO_{4}]$ = (1 - 0.392) mM

$[HPO_{4}]$ = 0.608 mM

Thus, we can conclude that concentration of the acid must be 0.608 mM.

7 0

2 years ago

At what temperature would a 1.50 m nacl solution freeze, given that the van't hoff factor for nacl is 1.9? kf for water is 1.86

IRINA_888 [86]

Win to ki ne lei ma ki mna mata ki ss kk

5 0

2 years ago

what is the specific latent heat of fusion for a substance that takes 550 kj to melt 14 kg at 262 k? brainly answers

Ket [755]

q = mL

L = q/m = 550 kJ/14 kg = 39 kJ/kg

3 0

2 years ago

Vsevolod [243]

Answer:

2 half-lives=0.8

6 half-lives= 0.05

Explanation

Half-lives are constant and always decrease by half, implying that the concentration decreases by half at a consistent rate.

3.2/2= 1.6/2= 0.8 is two half-lives

3.2/2= 1.6/2= 0.8/2= 0.4/2= 0.2/2= 0.1/2=0.05 is six half-lives

3 0

2 years ago

Calculate the percentage yield for the reaction represented by the equation CH4 + 2O2 ? 2H2O + CO2 when 1000 g of CH2 react with

makvit [3.9K]

Answer:

83.64%.

Explanation:

∵ The percent yield = (actual yield/theoretical yield)*100.

actual yield of CO₂ = 2300 g.

We need to find the theoretical yield of CO₂:

For the reaction:

CH₄ + 2O₂ → 2H₂O + CO₂,

1.0 mol of CH₄ react with 2 mol of O₂ to produce 2 mol of H₂O and 1.0 mol of CO₂.

Firstly, we need to calculate the no. of moles of 1000 g of CH₄ using the relation:

no. of moles of CH₄ = mass/molar mass = (1000 g)/(16.0 g/mol) = 62.5 mol.

Using cross-multiplication:

1.0 mol of CH₄ produces → 1.0 mol of CO₂, from stichiometry.

∴ 62.5 mol of CH₄ produces → 62.5 mol of CO₂.

We can calculate the theoretical yield of carbon dioxide gas using the relation:

∴ The theoretical yield of CO₂ gas = n*molar mass = (62.5 mol)(44.0 g/mol) = 2750 g.

∵ The percent yield = (actual yield/theoretical yield)*100.

actual yield = 2300 g, theoretical yield = 2750 g.

∴ the percent yield = (2300 g/2750 g)*100 = 83.64%.

5 0

3 years ago