If you want 1,775 mL of 48 M MgCl2 solution, how many grams of MgCl2 do you need?

A student is performing a titration to determine the concentration of a 20.0 mL sample of hydrochloric acid. What did the studen

irakobra [83]

Answer:

0.25M HCl

Explanation:

The reaction of HCl with NaOH is:

HCl + NaOH ⇄ H₂O + NaCl

Where 1 mole of HCl reacts per mole of NaOH

The end point was reached when the student added:

0.0500L × (0.1mol / L) = 0.00500 moles of NaOH

As 1 mole of HCl reacted per mole of NaOH, moles of HCl present are:

0.00500 moles HCl

The volume of the sample of hydrochloric acid was 20.0mL = 0.0200L, and concentration of the sample is:

0.00500 mol HCl / 0.0200L = 0.25M HCl

8 0

2 years ago

A 25 liter gas cylinder contains 10 mole of carbon dioxide. Calculate the pressure, in atm, of the gas at 325K.

Arada [10]

Answer: The pressure of carbon dioxide gas is 11 atm

Explanation:

To calculate the pressure of gas, we use the equation given by ideal gas equation:

PV = nRT

where,

P = pressure of the gas = ?

V = Volume of gas = 25 L

n = number of moles of gas = 10 mole

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the gas = 325 K

Putting values in above equation, we get:

$P\times 25L=10mol\times 0.0821\text{ L atm }mol^{-1}K^{-1}\times 325K\\\\P=11atm$

Hence, the pressure of carbon dioxide gas is 11 atm

4 0

3 years ago

In order to design an experiment, you need a ____ about the scientific question you are trying to answer. A. decision B. procedu

kolbaska11 [484]

The correct answer is option C, that is, hypothesis.

The hypothesis is the starting building block in the scientific method. It is also illustrated as an educated guess, based on previous observation and knowledge. A hypothesis refers to a recommended solution for an unexplained event, which does not fit into the present accepted scientific theory.

The fundamental concept of a hypothesis is that there is no pre-determined result. For a hypothesis to be considered as scientific hypothesis, it has to be something, which can be refuted or supported via carefully crafted observation or experimentation.

4 0

2 years ago

A student dissolves 15.0 g of ammonium chloride(NH4Cl) in 250. 0 g of water in a well-insulated open cup. She then observes the

iren2701 [21]

Answer:

1) Endothermic.

2) $Q_{rxn}=4435.04J$

3) $\Delta _rH=15.8kJ/mol$

Explanation:

Hello there!

1) In this case, for these calorimetry problems, we can realize that since the temperature decreases the reaction is endothermic because it is absorbing heat from the solution, that is why the temperature goes from 22.00 °C to 16.0°C.

2) Now, for the total heat released by the reaction, we first need to assume that all of it is released by the solution since it is possible to assume that the calorimeter is perfectly isolated. In such a way, it is also valid to assume that the specific heat of the solution is 4.184 J/(g°C) as it is mostly water, therefore, the heat released by the reaction is:

$Q_{rxn}=-(15.0g+250.0g)*4.184\frac{J}{g\°C}(16.0-20.0)\°C\\\\ Q_{rxn}=4435.04J$

3) Finally, since the enthalpy of reaction is calculated by dividing the heat released by the reaction over the moles of the solute, in this case NH4Cl, we proceed as follows:

$\Delta _rH=\frac{ Q_{rxn}}{n}\\\\\Delta _rH= \frac{ 4435.04J}{15.0g*\frac{1mol}{53.49g} } *\frac{1kJ}{1000J} \\\\\Delta _rH=15.8kJ/mol$

Best regards!

4 0

3 years ago

Which is a symbol that represents SI units for temperature.

dsp73

Answer:

A.'C

Explanation:

Please answer my question

5 0

3 years ago

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