1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
d1i1m1o1n [39]
3 years ago
15

Why should scientists perform experiments? A. To understand a hypothesis B. To answer questions about right and wrong C. To answ

er specific questions D. To impress their coworkers
Chemistry
1 answer:
marta [7]3 years ago
4 0

Answer:

C

Explanation:

they need to do this experiments in order to answer the questions the have though this experiments they can learn more and get more knowledge

You might be interested in
One of the radioactive isotopes used in medical treatment or analysis is chromium-51. The half-life of chromium-51 is 28 days. H
Goryan [66]

Answer : The time required for decay is, 84 days.

Explanation :

Half-life of chromium-51 = 28 days

First we have to calculate the rate constant, we use the formula :

k=\frac{0.693}{t_{1/2}}

k=\frac{0.693}{28\text{ days}}

k=0.0248\text{ days}^{-1}

Now we have to calculate the time required for decay.

Expression for rate law for first order kinetics is given by:

t=\frac{2.303}{k}\log\frac{a}{a-x}

where,

k = rate constant

t = time taken by sample = ?

a = let initial activity of the sample = 100

a - x = amount left after decay process  = 12.5

Now put all the given values in above equation, we get

t=\frac{2.303}{0.0248}\log\frac{100}{12.5}

t=83.9\text{ days}\approx 84\text{ days}

Therefore, the time required for decay is, 84 days.

7 0
3 years ago
Potassium nitrate has a lattice energy of -163.8 kcal/mol and a heat of hydration of -155.5 kcal/mol.
Brut [27]

Answer:

<em>293.99 g </em>

OR

<em>0.293 Kg</em>

Explanation:

Given data:

Lattice energy of Potassium nitrate (KNO3) = -163.8 kcal/mol

Heat of hydration of KNO3 = -155.5 kcal/mol

Heat to absorb by KNO3 = 101kJ

To find:

Mass of KNO3 to dissolve in water = ?

Solution:

Heat of solution = Hydration energy - Lattice energy

                           = -155.5 -(-163.8)

                           = 8.3 kcal/mol

We already know,

1 kcal/mol = 4.184 kJ/mole

Therefore,

= 4.184 kJ/mol x 8.3 kcal/mol

= 34.73 kJ/mol

Now, 34.73 kJ of heat is absorbed when 1 mole of KNO3 is dissolved in water.

For 101 kJ of heat would be

= 101/34.73

= 2.908 moles of KNO3

Molar mass of KNO3 = 101.1 g/mole

Mass of KNO3 = Molar mass x moles

                         = 101.1 g/mole  x  2.908

                         = 293.99 g

                         = 0.293 kg

<em><u>293.99 g potassium nitrate has to dissolve in water to absorb 101 kJ of heat. </u></em>     

4 0
3 years ago
Why is it not wise to make your bungee cord the same height of the building you plan to bungee jump from?
DIA [1.3K]
Because you won’t have enough time to stop and bounce back up before you hit the ground since the cord is the same length as the building.
5 0
3 years ago
Read 2 more answers
What is the simplest type of particle?
Fed [463]
Particle is more than an atom - a particle I beleive implies either a diatomic gas or just a plain old unbonded noble gas atom? hope this helped.
8 0
3 years ago
Read 2 more answers
HELP PLEASE I HAVE A TEST TODAY AND I DON'T UNDERSTAND ANY OF THIS...
myrzilka [38]

Answer:

About 67 grams or 67.39 grams

Explanation:

First you would have to remember a few things:

 enthalpy to melt ice is called enthalpy of fusion.  this value is 6.02kJ/mol

  of ice  

 it takes 4.18 joules to raise 1 gram of liquid water 1 degree C

 water boils at 100 degrees C and water melts above 0 degrees C

 1 kilojoules is 1000 joules

  water's enthalpy of vaporization (steam) is 40.68 kJ/mol

  a mole of water is 18.02 grams

  we also have to assume the ice is at 0 degrees C

Step 1

Now start with your ice.  The enthalpy of fusion for ice is calculated with this formula:

q = n x ΔH    q= energy, n = moles of water, ΔH=enthalpy of fusion

Calculate how many moles of ice you have:

150g x (1 mol / 18.02 g) = 8.32 moles

Put that into the equation:

q = 8.32 mol x 6.02 = 50.09 kJ of energy to melt 150g of ice

Step 2

To raise 1 gram of water to the boiling point, it would take 4.18 joules times 100 (degrees C)  or 418 joules.

So if it takes 418 joules for just 1 gram of water, it would take 150 times that amount to raise 150g to 100 degrees C.  418 x 150 = 62,700 joules or 62.7 kilojoules.

So far you have already used 50.09 kJ to melt the ice and another 62.7 kJ to bring the water to boiling.  That's a total of 112.79 kJ.

Step 3

The final step is to see how much energy is left to vaporize the water.

Subtract the energy you used so far from what you were told you have.

265 kJ - 112.79 kJ = 152.21 kJ

Again q = mol x ΔH (vaporization)

You know you only have 152.21 kJ left so find out how many moles that will vaporize.

152.21 kJ = mol x 40.68  or   mol = 152.21 / 40.68  = 3.74 moles

This tells you that you have vaporized 3.74 moles with the energy you have left.

Convert that back to grams.

3.74 mol   x  ( 18.02 g / 1 mol ) = 67.39 grams

5 0
2 years ago
Other questions:
  • The Bohr model of the Adam addressed the problem of
    6·1 answer
  • What is the enthalpy for reaction 1 reversed? reaction 1 reversed: 2CO2+3H2O→C2H5OH+3O2?
    11·2 answers
  • To engender means to _____.
    15·2 answers
  • What is the empirical formula for c12h24o6? what is the empirical formula for c12h24o6? ch2o cho c2h5o c2h4o cho2?
    13·1 answer
  • In the following reaction the iodide ion (I-) in HI is oxidized by the permanganate ion (MnO4-). A 5.0 mL solution of 0.20M HI r
    8·1 answer
  • How many liters of 1.88 M solution can be made with 29.5 grams of lithium fluoride?
    14·1 answer
  • A piece of metal with a mass of 147g and a volume of 21ml. Calculate the density of the metal.
    9·2 answers
  • One source of aluminum metal is alumina, Al2O3. a. Determine the percentage composition of Al in alumina. b. How many pounds of
    5·1 answer
  • The law of definite proportions states that______.
    15·1 answer
  • Mrs tuckers class is doing an experiment they fill up a cup with ice water they measure the temperature of both the water and th
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!