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kotegsom [21]
3 years ago
14

What is the percent by mass of nahco3 in a solution containing 10 g of nahco3 dissolved in 400 ml of h2o?

Chemistry
1 answer:
Marat540 [252]3 years ago
7 0
Answer is: the percent by mass of NaHCO₃ is 2,43%.
m(NaHCO₃) = 10 g.
V(H₂O) = 400 ml.
d(H₂O) = 1 g/ml.
m(H₂O) = V(H₂O) · d(H₂O).
m(H₂O) = 400 ml · 1 g/ml.
m(H₂O) = 400 g.
m(solution) = m(H₂O) + m(NaHCO₃).
m(solution) = 400 g + 10 g.
m(solution) = 410 g.
ω(NaHCO₃) = 10 g ÷ 410 g · 100%.
ω(NaHCO₃) = 2,43 %
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Calculate the ph of a 0.021 m nacn solution. [ka(hcn) = 4.9  10–10]
ohaa [14]

<span>Answer is: pH of solution of sodium cyanide is 11.3.
Chemical reaction 1: NaCN(aq) → CN</span>⁻(aq) + Na⁺<span>(aq).
Chemical reaction 2: CN</span>⁻ + H₂O(l) ⇄ HCN(aq) + OH⁻<span>(aq).
c(NaCN) = c(CN</span>⁻<span>) = 0.021 M.
Ka(HCN) =  4.9·10</span>⁻¹⁰<span>.
Kb(CN</span>⁻) = 10⁻¹⁴ ÷ 4.9·10⁻¹⁰ = 2.04·10⁻⁵<span>.
Kb = [HCN] · [OH</span>⁻] / [CN⁻<span>].
[HCN] · [OH</span>⁻<span>] = x.
[CN</span>⁻<span>] = 0.021 M - x..
2.04·10</span>⁻⁵<span> = x² / (0.021 M - x).
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4 0
3 years ago
Which of the following describes a scenario in which the molecular geometry would have the smallest bond angle(s)? (A) four bond
maw [93]

Answer: The correct answer is "B" two bonding domains(or bonding pairs) or two non bonding domains(or lone pairs)

Explanation:

Molecular geometry/structure is a three dimensional shape of a molecule. It is basically an arrangement of atoms in a molecule.It is determined by the central atom, its surrounding atoms and electron pairs.According to VSEPR theory, there are 5 basic shapes of a molecule: linear, trigonal planar, tetrahedral, trigonal bipyramidal and octahedral.

A)Four bonding domains and zero non bonding domains: shape is tetrahedral and bond angle is 109.5°

B)Two bonding domains and two non bonding domains(lone pairs): shape is bent and bond angle is 104.5°

C)Three bonding domains and one non bonding domain: shape is trigonal pyramidal and bond angle is 107°

D)Two bonding domain and zero non bonding domain: shape is linear and bond angle is 107°

E)Two bonding domain and one non bonding domain: bent shape and bond angle is 120°

F)Three bonding domains and zero nonbonding domain: shape is trigonal planar and bond angle is 120°

Hence Two bonding domains and two non bonding domains have the smallest bond angle.

6 0
3 years ago
Co(g) effuses at a rate that is ______ times that of cl2(g) under the same conditions.
il63 [147K]

Answer is: the ratio of the effusion rate is 1.59 : 1.

1) rate of effusion of carbon monoxide gas = 1/√M(CO).  

rate of effusion of carbon monoxide gas = 1/√28.

rate of effusion of carbon monoxide gas = 0.189.  

2) rate of effusion of chlorine = 1/√M(Cl₂).  

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rate of effusion of chlorine = 0.119.  

rate of effusion of carbon monoxide : rate of effusion of chlorine =

= 0.189 : 0.119 / ÷0.119.

rate of effusion of carbon monoxide : rate of effusion of chlorine = 1.59 : 1.

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