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3 years ago

Which statements correctly describe compounds? Check all that apply.

2 answers:

8 0

Compounds can be broken down into simpler substances by chemical means.

Each compound is composed of two or more types of atoms

In essence, compounds are chemicals that are composed of two or more atoms or elements. Compounds or molecules have a specific chemical formula, and have a definite and constant proportion of constituents.

Dafna1 [17]3 years ago

3 0

Answer:

Compounds can be broken down into simpler substances by chemical means.

Each compound is composed of two or more types of atoms

Explanation:

im doing a 50 question quiz and this is my answer

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What is the charge of a beta particle? 0 1– 2+ 4+

marusya05 [52]

Its 2+! Dont mind this hdhdhdjhdndbdbdbdbsnnsjdndsnjd

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3 years ago

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When baking soda (sodium bicarbonate or sodium hydrogen carbonate, NaHCO3) is heated, it releases carbon dioxide gas, which is r

butalik [34]

Answer:

There is 78.25g NaHCO3 required

Explanation:

Step 1: Balance the equation

2 NaHCO3 → Na2CO3 + CO2 + H20

For 2 moles of NaHCO3 consumed, there is produced 1 mole of Na2CO3, 1 mole of CO2 and 1 mole of H2O.

Step 2: calculating moles of CO2

mass of Co2 = 20.5g

Molar mass of CO2 = 44.01 g/mole

moles of CO2 = 20.5 / 44.01 = 0.4658 moles

Step 3: Calculating moles of NaHCO3

Since we have for 1 mole CO2 produced, there is 2 moles of NaHCO3 consumed.

To calculate number of moles of NaHCO3, we have to multiply the number of moles of CO2, by 2.

⇒ 0.4658 x2 = 0.9316 moles

Step 4: Calculating the mass of NaHCO3

mass of NaHCO3 = moles of NaHCO3 x Molar mass of NaHCO3

mass = 0.9316 moles x 84g/ mole = 78.25g NaHCO3

There is 78.25g NaHCO3 required

4 0

3 years ago

What mass of salt (nacl) should you add to 1.48 l of water in an ice cream maker to make a solution that freezes at -13.4 ∘c ? a

blagie [28]

Answer is: mass of salt is 311,15 g.
V(H₂O) = 1,48 l · 1000 ml/l = 1480 ml.
m(H₂O) = 1480 g = 1,48 kg.
d(solution) = 1,00 g/ml.
ΔT(solution) = 13,4°C = 13,4 K.
Kf = 1,86 K·kg/mol; cryoscopic constant of water
i(NaCl) = 2; Van 't Hoff factor.
ΔT(solution) = Kf · b · i.
b(NaCl) = 13,4 K ÷ (1,86 K·kg/mol · 2).
b(NaCl) = 3,6 mol/kg.
n(NaCl) = 3,6 mol · 1,48 kg= 5,328 mol.
m(NaCl) = 5,328 mol · 58,4 g/mol = 311,15 g.

5 0

3 years ago

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A mixture of gases with a pressure of 800.0 mm hg contains 60% nitrogen and 40% oxygen by volume. What is the partial pressure o

larisa86 [58]

Answer:

The partial pressure of oxygen in the mixture is 320.0 mm Hg

Explanation:

1) Take a base of 100 liters of mixture:

N: 60% × 100 liter = 60 liter

O: 40 % × 100 liter = 40 liter.

2) Volume fraction:

At constant pressure and temperature, the volume of a gas is proportional to the number of molecules.

Then, the mole ratio is equal to the volume ratio. Callin n₁ and n₂, the number of moles of nitrogen and oxygen, respectively, and V₁, V₂ the volume of the respective gases you can set the proportion:

V₁ / V₂ = n₁ / n₂

That means that the mole ratio is equal to the volume ratio, and the mole fraction is equal to the volume fraction.

Then, since the law of partial pressures of gases states that the partial pressure of each gas is equal to the mole fraction of the gas multiplied by the total pressure, you can draw the conclusion that the partial pressure of each gas is equal to the volume fraction of the gas in the mixture multiplied by the total pressure.

Then calculate the volume fractions:

Volume fraction of a gas = volume of the gas / volume of the mixture

N: 60 liter / 100 liter = 0.6 liter

V: 40 liter / 100 liter = 0.4 liter

3) Partial pressures:

These are the final calculations and results:

Partial pressure = volume fraction × total pressure

Partial pressure of N = 0.6 × 800.0 mm Hg = 480.0 mm Hg

Partial pressure of O = 0.4 × 800.0 mm Hg = 320.0 mm Hg

8 0

3 years ago

Use bond energies to calculate the enthalpy of reaction for the combustion of ethane. Average bond energies in kJ/mol C-C 347, C

ivanzaharov [21]

The enthalpy of reaction for the combustion of ethane 2CH₃CH₃ + 7O₂ → 4CO₂ + 6H₂O calculated from the average bond energies of the compounds is -2860 kJ/mol.

The reaction is:

2CH₃CH₃ + 7O₂ → 4CO₂ + 6H₂O (1)

The enthalpy of reaction (1) is given by:

$\Delta H = \Delta H_{r} - \Delta H_{p}$ (2)