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Alinara [238K]
3 years ago
12

A laboratory technician drops a 0.0850 kg sample of unknown material, at a temperature of 100.0∘C, into a calorimeter. The calor

imeter can, initially at 19.0∘C, is made of 0.150 kg of copper and contains 0.200 kg of water. The final temperature of the calorimeter can is 26.1∘C.
Chemistry
1 answer:
GREYUIT [131]3 years ago
5 0

Answer:

1013.32 J/kg.K

Explanation:

The heat transferred by a changing in temperature without phase change can be calculated by:

Q = m*c*ΔT

Where m is the mass, c is the specific heat, and ΔT is the change in temperature (final - initial).

The values of c for water and copper can e found in thermodynamics tables:

cwater = 4.19x10³ J/kg.K

ccopper = 0.39x10³ J/kg.k

By the conservation of energy:

Qwater + Qcopper + Qmaterial = 0

0.200*4.19x10³*(26.1 - 19.0) + 0.150*0.39x10³*(26.1 - 19.0) + 0.085*c*(26.1 - 100) = 0

5949.8 + 415.35 - 6.2815c = 0

6.2815c = 6365.15

c = 1013.32 J/kg.K

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Medicinal “ether" is produced when ethyl alcohol is treated with an acid. How many grams of
DochEvi [55]

Answer:

34.3 g

Explanation:

Step 1: Write the balanced equation

2 CH₃CH₂OH ⇒ CH₃CH₂OCH₂CH₃ + H₂O

Step 2: Calculate the moles corresponding to 50.0 g of CH₃CH₂OH

The molar mass of CH₃CH₂OH is 46.07 g/mol.

50.0 g × 1 mol/46.07 g = 1.09 mol

Step 3: Calculate the theoretical moles of CH₃CH₂OCH₂CH₃ produced

The molar ratio of CH₃CH₂OH to CH₃CH₂OCH₂CH₃ is 2:1. The moles of CH₃CH₂OCH₂CH₃ theoretically produced are 1/2 × 1.09 mol = 0.545 mol.

Step 4: Calculate the real moles of CH₃CH₂OCH₂CH₃ produced

The percent yield of the reaction is 85%.

0.545 mol × 85% = 0.463 mol

Step 5: Calculate the mass corresponding to 0.463 moles of CH₃CH₂OCH₂CH₃

The molar mass of CH₃CH₂OCH₂CH₃ is 74.12 g/mol.

0.463 mol × 74.12 g/mol = 34.3 g

6 0
3 years ago
Calculate the equilibrium number of vacancies per cubic meter for copper at 1000K. The energy for vacancy formation is 0.9eV/ato
nexus9112 [7]

Answer:

Therefore the equilibrium number of vacancies per unit cubic meter =2.34×10²⁴ vacancies/ mole

Explanation:

The equilibrium number of of vacancies is denoted by N_v.

It is depends on

  • total no. of atomic number(N)
  • energy required for vacancy
  • Boltzmann's constant (k)= 8.62×10⁻⁵ev K⁻¹
  • temperature (T).

N_v=Ne^{-\frac{Q_v}{kT} }

To find  equilibrium number of of vacancies we have find N.

N=\frac{N_A\ \rho}{A_{cu}}

Here ρ= 8.45 g/cm³  =8.45 ×10⁶m³

N_A= Avogadro Number = 6.023×10²³

A_{Cu}= 63.5 g/mole

N=\frac{6.023\times 10^{23}\times 8.45\times 10^{6}}{63.5}

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Here Q_v=0.9 ev/atom , T= 1000k

Therefore the equilibrium number of vacancies per unit cubic meter,

N_v=( 8.01\times 10^{28}) e^{-(\frac{0.9}{8.62\times10^{-5}\times 1000})

   =2.34×10²⁴ vacancies/ mole

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