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2 years ago

A student collected a total of 36.04 g of water from a reaction. What number of moles of water does this represent

1 answer:

4 0

To find the number of moles from a mass given, simply look to the formula n (moles) = m (mass, g) / MM (molar mass).
Mass was given, 36.04
Molar mass is the total atomic mass of all the atoms present. Water is H20, so that means 2 hydrogen and 1 oxygen. The atomic mass of hydrogen is 1 and atomic mass of oxygen is 16. Therefore MM= 1 + 1 + 16= 18.
Plug that value in and the full equation is
n = 36.04/18
n = 2.002 moles
= 2 moles

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The pKs of succinic acid are 4.21 and 5.64. How many grams of monosodium succinate (FW = 140 g/mol) and disodium succinate (FW =

Varvara68 [4.7K]

Answer:

9.744g of monosodium succinate.

4.925g of disodium succinate.

Explanation:

To find pH of the buffer produced by the mixture of monosodium succinate-Disodium succinate is obtained from H-H equation:

pH = pKa + log ([Na₂Suc] / [NaHSuc])

As you want a pH of 5.28 and pKa is 5.64:

5.28 = 5.64 + log ([Na₂Suc] / [NaHSuc])

-0.36 = log ([Na₂Suc] / [NaHSuc])

0.4365 = ([Na₂Suc] / [NaHSuc]) <em>(1)</em>

<em />

As total concentration of the buffer is 100mM = 0.100M:

0.100M = [Na₂Suc] + [NaHSuc] <em>(2)</em>

Replacing (2) in (1):

0.4365 = (0.100M - [NaHSuc] / [NaHSuc])

0.4365 [NaHSuc] = 0.100M - [NaHSuc]

1.4365 [NaHSuc] = 0.100M

[NaHSuc] = 0.0696M

And:

[Na₂Suc] = 0.0304M

As volume of the buffer is 1L:

[NaHSuc] = 0.0696 moles

[Na₂Suc] = 0.0304 moles

Using molar mass of both substances:

Mass of monosodium succinate:

0.0696moles * (140g / 1mol) =<em> 9.744g of monosodium succinate.</em>

Mass of disodium succinate:

0.0304moles * (162g / 1mol) =<em> 4.925g of disodium succinate.</em>

5 0

2 years ago

7. How many moles of argon are there in 20.0 L, at 25 degrees Celsius and 96.8 kPa?

suter [353]

<h3>Answer:</h3>

0.8133 mol

<h3>Solution:</h3>

Data Given:

Moles = n = ??

Temperature = T = 25 °C + 273.15 = 298.15 K

Pressure = P = 96.8 kPa = 0.955 atm

Volume = V = 20.0 L

Formula Used:

Let's assume that the Argon gas is acting as an Ideal gas, then according to Ideal Gas Equation,

P V = n R T

where; R = Universal Gas Constant = 0.082057 atm.L.mol⁻¹.K⁻¹

Solving Equation for n,

n = P V / R T

Putting Values,

n = (0.955 atm × 20.0 L) ÷ (0.082057 atm.L.mol⁻¹.K⁻¹ × 298.15 K)

n = 0.8133 mol

4 0

2 years ago

Read 2 more answers

Calculate δg o for each reaction using δg of values:(a) h2(g) + i2(s) → 2hi(g) kj (b) mno2(s) + 2co(g) → mn(s) + 2co2(g) kj (c)

steposvetlana [31]

Part (a) :
H₂(g) + I₂(s) → 2 HI(g)
From given table:
G HI = + 1.3 kJ/mol
G H₂ = 0
G I₂ = 0
ΔG = G(products) - G(reactants) = 2 (1.3) = 2.6 kJ/mol

Part (b):
MnO₂(s) + 2 CO(g) → Mn(s) + 2 CO₂(g)
G MnO₂ = - 465.2
G CO = -137.16
G CO₂ = - 394.39
G Mn = 0
ΔG = G(products) - G(reactants) = (1(0) + 2*-394.39) - (-465.2 + 2*-137.16) = - 49.3 kJ/mol

Part (c):
NH₄Cl(s) → NH₃(g) + HCl(g)
ΔG = ΔH - T ΔS
ΔG = (H(products) - H(reactants)) - 298 * (S(products) - S(reactants))
= (-92.31 - 45.94) - (-314.4) - (298 k) * (192.3 + 186.8 - 94.6) J/K
= 176.15 kJ - 84.78 kJ = 91.38 kJ

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2 years ago

Read 2 more answers

Diano4ka-milaya [45]

Answer:

The advantage of net ionic equations is that they show only those species that are directly involved in the reaction

Explanation:

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2 years ago

Which statement describes the relative energy of the electrons in the shells of a calcium atom?

Zina [86]

The answer is (3) An electron in the third shell has more energy than an electron in the second shell. The energy of electron will increase when number of shell increase.

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2 years ago