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aksik
3 months ago
14

What mass of water freezes if 5.43 kJ oh heat are released in the process

Chemistry
1 answer:
Anarel [2.9K]3 months ago
6 0
Q= mass•specific heat•change temp. 5.43=m•4.184•(202-32) M=7.63grams
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(a) The mass density of a gaseous compound was found to be 1.23 kg m^−3 at 330 K and 20 kPa. What is the molar mass of the compo
castortr0y [3046]

Answer:

La masa molar del compuesto es: 168.82 g/mol

La masa molar del gas es: 16.38 g/mol

Explanation:

(a)

Utilizando la ecuación de gases ideales:

PV=nRT

donde,

P es la presión

V es el volumen

n es el número de moles

T es la temperatura

R es la constante de los gases, cuyo valor es = 0.0821 L.atm/K.mol

Además,

Moles = masa (m) / Masa molar (M)

La densidad (d) = Masa (m) / Volumen (V)

Así, la ecuación de gases ideales se puede expresar como:

PM=dRt

Dado que:-

Presión = 20 kPa = 20000 Pa

La expresión para la conversión de presión en Pascal a presión en atm se muestra a continuación:

P (Pa) = \frac {1}{101325} P (atm)

20000 Pa = \frac {20000}{101325} atm

Presión = 0.1974 atm

Temperatura = 330 K

d = 1.23 kg/m³ = 1.23 g/L

Masa molar =?

Aplica la fórmula:

0.1974 atm × M = 1.23 g/L × 0.0821 L.atm/K.mol × 330 K

⇒M = 168.82 g/mol

La masa molar del compuesto es: 168.82 g/mol

(b)

Dado que:

Presión = 152 Torr

Temperatura = 298 K

Volumen = 250 cm³ = 0.25 L

Utilizando la ecuación de gases ideales:

PV=nRT

R = 62.3637\text{torr}mol^{-1}K^{-1}

Aplicando la fórmula:

152 Torr × 0.25 L = n × 62.3637 L.torr/K.mol × 298 K

⇒n = 0.002045 moles

Dado que:

Masa del gas = 33.5 mg = 0.0335 g

Masa molar =?

La fórmula para calcular los moles se muestra a continuación:

moles = \frac{Mass\ taken}{Molar\ mass}

Así,

0.002045\ moles
= \frac{0.0335\ g}{Molar\ mass}

La masa molar del gas es: 16.38 g/mol

5 0
3 months ago
In an experiment a student mixes a 50.0 mL sample of 0.100 M AgNO₃(aq) with a 50.0 mL sample of 0.100 M NaCl(aq) at 20.0°C in a
KiRa [2933]

The enthalpy change associated with the precipitation reaction is 84 kJ/mole

Why?

The chemical equation for the reaction can be written as

AgNO₃(aq) + NaCl (aq) → AgCl(s) + NaNO₃(aq)

To determine the enthalpy change, the following equation applies

\Delta H =\frac{Q}{n}

To calculate the heat (Q):

Q=m*C*\Delta T=(100g)*(4.2 J/g*^\circ C)*(21^\circ C-20^\circ C)\\\\Q=420J

Next, we need to calculate the number of moles involved in the reaction (n):

n=[AgNO_3]*v(L)=(0.1M)*(0.05L)=0.005moles

With these two values, we can substitute them into the first equation:

\Delta H= \frac{420J}{0.005moles}=84000J/mole=84kJ/mole

Have a great day!

5 0
3 months ago
A 92.8 gram sample of Ba(OH)2•4H2O (barium hydroxide tetrahydrate) is heated until water is released. How many grams of water we
Alekssandra [3086]

According to the periodic table:
the molar mass of barium is 137.2 grams
the molar mass of oxygen is 16 grams
the molar mass of hydrogen is 1 gram

The molar mass of Ba(OH)2 can be calculated as 137.2 + 2(16) + 2(1) = 171.2 grams.
The molar mass of 4H2O is computed as 4 [2(1) + 16] = 72 grams.

Consequently, the molar mass of Ba(OH)2·4H2O is 171.2 + 72 = 243.2 grams.

Therefore, a sample weighing 243.2 grams of <span>barium hydroxide tetrahydrate includes 72 grams of water, meaning that within 92.8 grams, the mass of water would be:
mass of water in 92.8 grams = (92.8 x 72) / 243.2 = 27.474 grams.

Thus, when heating a 92.8 gram sample of Ba(OH)2·4H2O (barium hydroxide tetrahydrate), 27.474 grams of water will be emitted.</span>

5 0
3 months ago
In Millikan’s experiment, the oil droplets acquire one or more negative charges by combining with the negative charges that are
lions [2927]
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4 0
2 months ago
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