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4 years ago

Which of the following is kept constant when using a coffee cup calorimeter? Temperature Density Mass Pressure

Chemistry

2 answers:

eduard4 years ago

5 0

The answer is pressure

SOVA2 [1]4 years ago

4 0

Answer:

Pressure

Explanation:

A coffee-cup calorimeter is essentially a constant-pressure calorimeter which is used to measure the enthalpy change (ΔH) in a solution. It comprises of a system of 2 nested styrofoam cups containing water which absorbs the heat from the reaction. A thermometer is inserted through the lid of the cup to record the changes in temperature.

Thus, the heat flow measured at constant pressure, q(p) is the enthalpy change (ΔH) of the reaction

$q_{p}=\Delta H$

The amount of heat absorbed or evolved during a reaction is related to the mass of the substance(m), specific heat capacity (c) and the change in temperature, ΔT

$q_{p}=\Delta H = mc\Delta T$

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How many grams of hydrogen chloride can be produced from 1g of hydrogen and 55g of chlorine? What is the limiting reactant?

vova2212 [387]

Answer:

The limiting reactant is hydrogen, and the grams HCl produced is 36.175 g.

Explanation:

Balanced equation is 2 H + Cl2 = 2 HCl.

First thing, convert grams to moles via using molar mass.

Molar mass for hydrogen is 1.0079 g/mol. 1g x 1 mol / 1.0079 g = 0.99216 mol.

Molar mass for chlorine is 70.906 g/mol. 55g x 1 mol / 70.906 g = 0.7756748 mol.

Next, determine which is the limiting reactant - probably the fastest way to do it is just to take one of the reactants, say it's the limiting one, and calculate how much of the other reactant would be needed if that really was the limiting reactant, and then compare it to the actual moles of reactant available.

If hydrogen was the limiting reactant at 0.992 mol, you'd need .496 mol of Cl2 to complete the reaction.

If chloride was the limiting reactant at 0.776 mol, you'd need 1.55 mol of H to complete the reaction.

Comparing these numbers to the amounts we actually have available, the limiting reactant is hydrogen.

Once you've determined that, just plug in the amounts to the balanced equation to get the number of moles of HCL produced, which in this case, is just 0.992 mol.

Now, reverse the process that you took to get the moles of reactant, and you have the grams of product produced.

0.992 mol x 36.4609 g / 1 mol = 36.175 g.

7 0

3 years ago

Question 1 of 15 2 Points What is another name for a pure substance? Answer here

maksim [4K]

Answer:

element

Explanation:

elements consist of pure substances

4 0

3 years ago

Р + 02 = P4O6 balance the equation

sergejj [24]

To balance a chemical equation, both sides should have equal mass, or in other words both sides should have same number of atoms as to follow the conservation of mass rule.

P + O₂ = P₄O₆

LHS:

Number of Phosphorus atoms = 1 atom

Number of Oxygen atoms = 2 atoms

RHS:

Number of Phosphorous atoms = 4 atoms

Number of Oxygen atoms = 6 atoms

Also since P₄O₆ has the most number of atoms we will make the LHS equalize to P₄O₆.

Difference between Phosphorous atoms in LHS to RHS = 3

Since phosphorous is a monatomic we need 3 phosphorous atoms extra

Difference between Oxygen atoms is LHS to RHS = 4

But Oxygen is diatomic, so we need 4/2 = 2 Oxygen molecules

Now lets see if it is balanced

P + 3P + O₂ + 2O₂ -------> P₄O₆

4P + 3O₂ ------> P₄O₆

LHS:

Phosphorous atoms = 4 atoms

Oxygen atoms = 3 × 2 = 6 atoms

RHS:

Phosphorous atoms = 4 atoms

Oxygen atoms = 6 atoms

LHS = RHS

Therefore the balanced equation is 4P + 3O₂ = P₄O₆

Happy to help :)

If you need more explanation or help in any other question, feel free to ask

3 0

3 years ago

1. Which of the following elements is a transition metal?

Orlov [11]

Where are the following elements to choose from?

8 0

3 years ago

Read 2 more answers

How many moles of water h2o are present in 75.0 g h2o?

nikklg [1K]

4.17 moles. Good luck! :)

7 0

3 years ago