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katovenus [111]
1 year ago
14

A 0.89% (w/v) sodium chloride solution is referred to as physiological saline solution because it has the same concentration of

salts as human blood. what is the molarity of a physiological saline solution? (note: w/v means mass to volume)
Chemistry
1 answer:
maks197457 [2]1 year ago
4 0
1) 0.89% m/v = 0.89 grams of NaCl / 100 ml of solution

=> 8.9 grams of NaCl in 1000 ml of solution = 8.9 grams of NaCl in 1 liter of solution

2) Molarity = M = number of moles of solute / liters of solution

=> calculate the number of moles of 8.9 grams of NaCl

3) molar mass of NaCl = 23.0 g /mol + 35.5 g/mol = 58.5 g / mol

4) number of moles of NaCl = mass / molar mass = 8.9 g / 58.5 g / mol = 0.152 mol

5) M = 0.152 mol NaCl / 1 liter solution = 0.152 M

Answer: 0.152 M
You might be interested in
12. Penny can knit 4 rows of a sweater in 5
Evgesh-ka [11]

Answer:

6.25 hours

Explanation:

From the question;

  • Penny can knit 4 rows in 5 minutes

We need to determine the time it will take for her to knit 300 rows

4 rows = 5 minutes

300 rows = ?

= (300 × 5 ) ÷ 4

= 375 minutes

But, 1 hour = 60 minutes

Therefore;

= 375 ÷ 60

= 6.25 hours

Thus, it will take penny 6.25 hours to knit 300 rows

8 0
1 year ago
Q1) A vapor-compression refrigeration system operates on the cycle of Fig. 9.1. The refrigerant is 1,1,1,2-Tetrafluoroethane. Gi
hoa [83]

Answer:

i)   0.5071 (kg/s)

ii)  -1407.1 kj/kg

iii)  204.05 Kw

iv)  5.881

v)    9.238

Explanation:

Given Data:

evaporation temperature ( T ) = 4°c = 277.15 K

Condensation Temperature ( T ) = 34°c = 307.15 K

<em>n</em> ( compressor efficiency ) = 0.76

refrigeration rate = 1200 kJ.s^-1

i) determine the circulation rate of the refrigerant

m = \frac{Q}{H2 - H1}  = \frac{Q}{H2 - H4\\}  ------- 1

Q = 1200 Kj.s^-1

H2 = entropy at step 2 = 2508.9 (kJ / kg ) ( gotten from Table F )

H4 = entropy at step 4 = 142.4 ( kJ/ kg )

back to equation 1

m ( circulation rate of refrigerant ) = 0.5071 (kg/s)

ii) heat transfer rate in the condenser

Q = m ( H4 - H3 )

    = 0.5071 ( 142.4 - 2911.27 )

    = -1407.1 kj/kg

where H3 = H2 + ΔH23 = 2911.27 (kj/kg) ( as calculated )

iii) power requirement

w = m * ΔH23

   = 0.5071 (kg/s) * 402.37 (kj/kg) =  204.05 Kw

where: ΔH23 = \frac{H'3 - H2 }{0.76} = \frac{2814.7-2508.9}{0.76} = 402.37 (kj/kg)

iv) coefficient of performance of a cycle

W = Qc / w

  = 1200 Kj.s^-1/ 204.05 kw

  = 5.881

v) coefficient of performance of a Carnot refrigeration cycle

w_{carnot} = \frac{T2}{T4 - T2}

            =  277.15 / ( 307.15 - 277.15 )

            = 9.238

4 0
2 years ago
An unknown solid is entirely soluble in water. On addition of dilute HCl, a precipitate forms. After the precipitate is filtered
Karo-lina-s [1.5K]

Answer:

Pb(NO3)2

Cd(NO3)2

Na2SO4

Explanation:

In the first part, addition of HCl leads to the formation of PbCl2 which is poorly soluble in water. This is the first precipitate that is filtered off.

When the pH is adjusted to 1 and H2S is bubbled in, CdS is formed. This is the second precipitate that is filtered off.

After this precipitate has been filtered off and the pH is adjusted to 8, addition of H2S and (NH4)2HPO4 does not lead to the formation of any other precipitate.

The yellow flame colour indicates the presence of Na^+ which must come from the presence of Na2SO4.

5 0
1 year ago
In each row, check the box under the compound that can reasonably be expected to be more acidic in aqueous solution, e.g. have t
vredina [299]

Answer:

HCH_{3}SO_{2}

H_{3}PO_{3}

HClO_{2}

Explanation:

Every acid (HA) tends to disolve into proton (H^{+}) and anion (A^{-}) in aqueous solution. Acid strength can be determined by measuring this tendency to separate into proton an anion. Strength of an acid can be quantified by its acid dissociation value - Ka. A strong acid will have a tendency to easily release proton and will have larger Ka value and smaller logarithmic value (pKa = - logKa) similar to calculating pH of the solution. So the easiest way to resolve this issue is by looking for Ka or pKa value of the acid (This table may be useful in more complex tasks and is attached below). However, stronger acid can be determined elsehow.

a) Carbon is element 14 with 4 valent electrons and sulfur is element 16 with 6 valence electrons. Thus, sulfur has stronger electronegativity (tendency to attract bonded electrons towards itself). This means that sulfur will hold oxygen tighter to itself so the hydrogen bond to it can be more easily separated from it. HCH_{3}SO_{2} is more acidic in aqueous solution.

b) In H_{3}PO_{4}, phosphorus holds one double bond with oxygen and three OH group equally. To show an acidic tendency, phosphorus would need to let go one hydrogen out of one of OH groups. In H_{3}PO_{3}, phosporus holds two double bong with oxygen, one OH and one hydrogen, all single and lonely, ready to leave phosphorus and show acidic characteristics in aqueous solution. Thus, H_{3}PO_{3} is more acidic compound.

C) In all Cl acids, the electron density is placed around Cl so the more oxygen around Cl, the more acidic will be the chemical. This is comparable to an oxidation state - the bigger oxidation state, the stronger acid will be:

HClO_{4}  ^{+7} >HClO_{3}^{+5} >HClO_{2}^{+3} >HClO_{}^{+1}

HClO_{2} can reasonably be expected to be more acidic in aqueous solution.

4 0
2 years ago
The electron configuration of an element is 1s22s22p4. Describe what most likely happens when two atoms of this element move tow
Vlad1618 [11]

Answer:

When the two atoms move towards each other a compound is formed by sharing electron pairs supplied by each of the atoms to enable them have the stable 8 (octet) valency electrons in their outermost shell

Explanation:

The electronic configuration of the given element can be written as follows;

1s²2s²2p⁴

The given electronic configuration is equivalent to that of oxygen, therefore, we have;

The number of electrons in the valence shell = 2 + 4 = 6 electrons

Therefore, each atom requires 2 electrons to complete its 8 (octet) electrons in the outermost shell

When the two atoms move towards each other, they react and combine to form a compound by sharing 4 electrons, 2 from each atom, such that each atom can have an extra 2 electrons in its outermost orbit in the newly formed compound and the stable octet configuration is attained by each of the atoms in the newly formed compound.

4 0
1 year ago
Read 2 more answers
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