Which group on the Periodic Table reacts violently with water by igniting hydrogen gas?

How would you prepare 3.5 L of a 0.9M solution of KCl?

PolarNik [594]

$V=3,5L\\
Cm=0,9M\\
M_{KCl}=74\frac{g}{mol}\\\\
C_{m}=\frac{n}{V}\\\\
n=\frac{m}{M}\\\\
C_{m}=\frac{m}{MV} \ \ \ \Rightarrow \ \ \ m=C_{m}MV\\\\
m=0,9\grac{mol}{L}*74\frac{g}{mol}*3,5L=233,1g$

B. Add 233 g of KCl to a 3.5 L container; then add enough water to dissolve the KCl and fill the container to the 3.5 L mark.

4 0

3 years ago

5. How many atoms of hydrogen are in a molecule of acetic acid (HC2H202)?

Kazeer [188]

Answer:

in acetic acid ,there are 4 hydrogen atoms

Explanation:

C H 3 C O O H

3 0

3 years ago

Can u please help me I don't understand it and if I don't do it my teacher will get really mad at me pleas

Nana76 [90]

Physical Change: It is a type of change in which matter changes its physical state like shape, size but is not transformed into another substance. It is usually a reversible process.

Chemical Change: It is a type of change in which the rearrangement of atoms of one or more than one substance is involved. and it changes its chemical composition that is there is a formation of at least one new substance. It is usually an irreversible process.

Now, keeping in mind the definitions, we can easily classify the examples in the question as physical or chemical change.

7. Chemical Change

8. Chemical Change

9. Physical Change

10. Chemical Change

11. Physical Change

12. Physical Change

13. Chemical Change

14. Physical Change

15. Chemical Change

16. Physical Change

17. Chemical Change

18. Chemical Change

19. Physical Change

20. Physical Change

21. Chemical Change

22. Physical Change

23. Chemical Change

24. Chemical Change

25. Physical Change

6 0

3 years ago

How can a scientist make sure that the results are not a mistake in an experiment?

olga55 [171]

Repeat trials multiple times

8 0

3 years ago

When 20.0 g of KI are dissolved in 50.0 mL of distilled water in a calorimeter, the temperature drops from 24.0 °C to 19.0 °C. C

Reil [10]

<h2>Answer:</h2>

<h2>Explanations</h2>

The formula for calculating the amount of heat absorbed by the water is given as:

$\begin{gathered} q=mc\triangle t \\ q=50\times4.18\frac{J}{g^oC}\times(19-24) \\ q=50\times4.18\times(-5) \\ q=-1045Joules \\ q=-1.045kJ \end{gathered}$

Determine the moles of KI

$\begin{gathered} moles\text{ of KI}=\frac{mass\text{ of KI}}{molar\text{ mass of KI}} \\ moles\text{ of KI}=\frac{20g}{166g\text{/mol}} \\ moles\text{ of KI}=0.1205moles \end{gathered}$

Since heat is lost, hence the enthalpy change of the solution will be negative that is:

$\begin{gathered} \triangle H=-q \\ \triangle H=-(-1.045kJ) \\ \triangle H=1.045kJ \end{gathered}$

Determine the enthalpy of solution in kJ•mol-1

$\begin{gathered} \triangle H_{diss}=\frac{1.045kJ}{0.1205mole} \\ \triangle H_{diss}\approx8.67kJmol^{-1} \end{gathered}$

Hence the enthalpy of solution in kJ•mol-1 for KI is 8.67kJ/mol

4 0

11 months ago