When lewis structures are drawn, do you only show valence electrons??

A chemistry student weighs out of chloroacetic acid into a volumetric flask and dilutes to the mark with distilled water. He pla

Nitella [24]

Answer:

11.6mL of the 0.1400M NaOH solution

Explanation:

<em>0.154g of chloroacetic acid diluted to 250mL. Titrated wit 0.1400M NaOH solution.</em>

<em />

The reaction of chloroacetic acid, ClCH₂COOH (Molar mass: 94.5g/mol) with NaOH is:

ClCH₂COOH + NaOH → ClCH₂COO⁻ + Na⁺ + H₂O

<em>Where 1 mole of the acid reacts per mole of the base.</em>

<em />

That means the student will reach equivalence point when moles of chloroacetic acid = moles NaOH.

You will titrate the 0.154g of ClCH₂COOH. In moles (Using molar mass) are:

0.154g ₓ (1mol / 94.5g) = <em>1.63x10⁻³ moles of ClCH₂COOH</em>

To reach equivalence point, the student must add 1.63x10⁻³ moles of NaOH. These moles comes from:

1.63x10⁻³ moles of NaOH ₓ (1L / 0.1400moles NaOH) = 0.0116L of the 0.1400M NaOH =

<h3>11.6mL of the 0.1400M NaOH solution</h3>

5 0

3 years ago

The first excited electronic energy level of the helium atom is 3.13 x 10-18 J above the ground level. Estimate the temperature

salantis [7]

Answer:

75603.86473 K

Explanation:

Given that:

The 1st excited electronic energy level of He atom = 3.13 × 10⁻¹⁸ J

The objective of this question is to estimate the temperature at which the ratio of the population will be 5.0 between the first excited state to the ground state.

The formula for estimating the ratio of population in 1st excited state to the ground state can be computed as:

$\dfrac{N_2}{N_1} = e ^{^{-\dfrac{(E_2-E_1)}{KT}}} = e ^{^{-\dfrac{(\Delta E)}{KT}}}$

From the above equation:

Δ E = energy difference = 3.13 × 10⁻¹⁸ J

k = Boltzmann constant = 1.38 × 10⁻²³ J/K

$\dfrac{N_2}{N_1} = 0.5$

Thus:

$0.05 =e^{^{ -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}$

$In (0.05) = { -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}$

$-3.00 = { -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}$

$-3.00 = -226811.5942 \times \dfrac{1}{T}$

$T = \dfrac{-226811.5942}{-3.00 }$

T = 75603.86473 K

4 0

3 years ago

You want to determine the protein content in milk with the Kjeldahl method. You take 100 g whole milk and use 100 mL of 0.5 M hy

stepladder [879]

Answer:

3.38%

Explanation:

Given that;

the mass of the whole milk sample = 100 g

volume of HCl = 100 mL = 0.1 L

molarity of HCl = 0.5 M

volume of NaOH = 34.50 mL = 0.0345 L

molarity of NaOH = 0.3512 M

Since we knew the molarity and volume of both HCl and NaOH; we can calculate their corresponding number of moles present.

So, number of moles of HCl = molarity of HCl × volume of HCl

number of moles of HCl = 0.5 M × 0.100 mL

= 0.05 mole

number of moles of NaOH = Molarity of NaOH × Volume of NaOH

number of moles of NaOH = 0.3512 M × 0.0345 L

= 0.012 mole

From the question, we can deduce that the number of HCl that is consumed by NH₃ is equal to the number of moles of HCl that is consumed by NaOH.

SO, number of moles of HCl consumed by NH₃ = Total moles of HCl - moles of HCl consumed by NaOH

= 0.05 mole - 0.012 mole

= 0.038 mole

However, to determine the mole of NH₃ present , we have:

number of moles of NH₃ present = number of moles of HCl consumed by NH₃ = 0.038

∴ the mass of Nitrogen with the molecular weight (14.0 g/mol) = 0.038 moles × 14.0 g/mol

= 0.530 g

Now, the percentage of Nitrogen can be calculated as;

$percentage of nitrogen =\frac{mass of nitrogen}{mass of the whole milk sample} *100$

$percentage of nitrogen =\frac{0.530g}{100g} *100$

$percentage of nitrogen =0.530%$ %

the percentage of protein in the sample = CP × %age of N

where CP is given as 6.38

∴ the percentage of protein in the sample = 6.38 × 0.530%

the percentage of protein in the sample = 3.3814%

the percentage of protein in the sample = 3.38%

6 0

3 years ago

Pls help !! it’s a timed quiz answer

inysia [295]

There are 6 Nitrogen atoms

6 0

2 years ago

The difference between asexual and sexual reproduction is _______. Please help me with this, thank you.

Alecsey [184]

Answer:

hope this helped.

Explanation:

Sexual reproduction just means combining genetic material from two parents. Asexual reproduction produces offspring genetically identical to the one parent.

4 0

3 years ago