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3 years ago

Which statement is not true about the periodic table?

1 answer:

4 0

Answer is A
All elements on the periodic table have a different number of protons that can be represented by its atomic number

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One and a half gallons of paint are used on refrigeration units which are then baked dry in a 275F oven for 2 hours. If the pain

brilliants [131]

Answer:

Hence the evaporation rate in pints per minute is 0.001583.

Explanation:

Now,

1.5 gallons of paint are used.

It has 5% solid, so total 95% of 1.5 gallon can evaporate(only the solvent part will evaporate).

95% of 1.5 gallon=(95/100)*1.5 = 1.425 gallons.

1gallon = 8 pints.

So 1.425 gallons=8*1.425 pints

=11.4 pints.

Evaporation requires 2 hours. That is 3600*2 seconds = 7200 seconds.

So evaporation rate= 11.4 pints/7200 seconds.

=0.001583 pints per second

4 0

3 years ago

When a student mixes 50 mL of 1.0 M HCl and 50 mL of 1.0 M NaOH in a coffee-cup calorimeter, the temperature of the resultant so

zmey [24]

Answer: 54.4 kJ/mol

Explanation:

First we have to calculate the moles of HCl and NaOH.

$\text{Moles of HCl}=\text{Concentration of HCl}\times \text{Volume of solution}=1.0M\times 0.05=0.05mole$

$\text{Moles of NaOH}=\text{Concentration of NaOH}\times \text{Volume of solution}=1.0\times 0.05L=0.05mole$

The balanced chemical reaction will be,

$HCl+NaOH\rightarrow NaCl+H_2O$

From the balanced reaction we conclude that,

As, 1 mole of HCl neutralizes by 1 mole of NaOH

So, 0.05 mole of HCl neutralizes by 0.05 mole of NaOH

Thus, the number of neutralized moles = 0.05 mole

Now we have to calculate the mass of water:

As we know that the density of water is 1 g/ml. So, the mass of water will be:

The volume of water = $50ml+50ml=100ml$

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/ml\times 100ml=100g$

Now we have to calculate the heat absorbed during the reaction.

$q=m\times c\times (T_{final}-T_{initial})$

where,

q = heat absorbed = ?

$c$ = specific heat of water = $4.18J/g^oC$

m = mass of water = 100 g

$T_{final}$ = final temperature of water = $27.5^0C$

$T_{initial}$ = initial temperature of metal = $21.0^0C$

Now put all the given values in the above formula, we get:

$q=100g\times 4.18J/g^oC\times (27.5-21.0)^0C$

$q=2719.6J=2.72kJ$

Thus, the heat released during the neutralization = 2.72 KJ

Now we have to calculate the enthalpy of neutralization per mole of $HCl$ :

0.05 moles of $HCl$ releases heat = 2.72 KJ

1 mole of $HCl$ releases heat = $\frac{2.72}{0.05}\times 1=54.4KJ$

Thus the enthalpy change for the reaction in kJ per mol of HCl is 54.4 kJ

6 0

3 years ago

Read 2 more answers

How many moles are 21.67 L of NH4CI?<br> Type your answer...

NNADVOKAT [17]

Answer:

0.967mole

Explanation:

Given parameters:

Volume of NH₄Cl = 21.67L

Unknown:

Number of moles = ?

Solution:

We assume that the volume was taken at standard temperature and pressure,

Then;

Number of moles = $\frac{volume }{22.4L}$

Number of moles = $\frac{21.67}{22.4}$ = 0.967mole

6 0

3 years ago

Convert 565,900 seconds into days

Andreas93 [3]

There are 60 seconds in one minute

565900 / 60 = 9431.667 minutes in 565,900 seconds

There are 60 minutes in an hour

9431.667 minutes / 60 = 157.9144 hours in 565900 seconds

There are 24 hours in 1 day

157.9144 hours / 24 hours = 6.5498 days.

4 0

3 years ago

Which of the following statements is true?

dybincka [34]

Answer:C

Explanation:

A process is called spontaneous if the process takes place on its own without the intervention of external factors.

The spontaneous processes are generally quick with observable rates of reaction.But processes can be spontaneous even with negligible rates of reaction.

Spontaneity of reactions depend on temperature.

This is because spontaneity is measured by gibbs energy or enthalpy.

Both of these measures are dependent on temperature.

So,temperature affects spontaneity.

7 0

3 years ago