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Travka [436]
2 years ago
7

can someone help me with these? I just started chemistry this semester, and since it's involving math I don't see myself doing g

ood.

Chemistry
1 answer:
V125BC [204]2 years ago
4 0

Any non zero digits are significant. (120 has 2 sig figs)

Zeroes between significant digits are significant. (103 has 3 sig figs)

Zeroes only count if there is a decimal point and if they are following a significant digit. (.600 has 3 sig figs; .067 has 2 sig figs)

1) <u>1278.50</u> = 6 sig figs

2) <u>12</u>0000 = 2 sig figs

3) <u>90027.00</u> = 7 sig figs

4) 0.00<u>53567</u> = 5 sig figs

5) <u>67</u>0 = 2 sig figs

6) 0.00<u>730</u> = 3 sig figs

That's all I'm gonna do so yeah.

Now for the rounding, it's basically rounding but it must have the x amount of sig figs after rounding. It's pretty hard to explain.

19, I'm not really sure. Might be 120 with a decimal point at the end.

20) 5.457, alright so here, since we are rounding to three significant digits, we look at the third sig fig. The third sig fig here would be 5. Then we just round. Since the number next to 5 is 7, we round 5 up to 6.

So 5.457 rounded to 3 sig figs would be 5.46

21) 0.0008769, the third sig fig here would be 6. You round 6 up to 7 because the number next to it is 9.

So 0.0008769 rounded to 3 sig figs would be 0.000877

So I hope you get it, I'm gonna let you do the rest.

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Nataly_w [17]

The metal is lead, Pb.

One unit of the oxide contains one atom of O (16.00 u).

∴ Mass of oxide = 16.00 u O × (100 u MO/7.17 u O) = 223.15 u MO

Mass of M = mass of MO – mass of O = 223.15 u -16.00 u = 207.2 u

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Periodic table 50 elements with thier valancies​
Lubov Fominskaja [6]

Answer:

The first 50 elements along with their valences are given below :

1. Hydrogen = 1

2. Helium = 0

3. Lithium = 1

4. Beryllium = 2

5. Boron = 3

6. Carbon = 4

7. Nitrogen = 3

8. Oxygen = 2

9. Fluorine = 1

10. Neon = 0

11. Sodium = 1

12. Magnesium = 2

13. Aluminium = 3

14. Silicon = 4

15. Phosphorus = 3

16. Sulphur = 2

17. Chlorine = 1

18. Argon = 0

19. Potassium = 1

20. Calcium = 2

21. Scandiun = 3

22. Titanium = 3

23. Vanadium = 4

24. Chromium = 3

25. Manganese = 4

26. Iron = 2

27. Cobalt = 2

28. Nickel = 2

29. Copper = 2

30. Zinc = 2

31. Gallium = 3

32. Germanium = 4

33. Arsenic = 3

34. Selenium = 2

35. Bromine = 1

36. Krypton = 0

37. Rubidium = 1

38. Strontium = 2

39. Yttrium = 3

40. Zirconium = 4

41. Niobium = 3

42. Molybdenum = 3

43. Technetium = 7

44. Ruthenium = 4

45. Rhodium = 3

46. Palladium = 4

47. Sliver = 1

48. Cadmium = 2

49. Indium = 3

50. Tin = 4

<u>Note</u> :

An element like Iron, copper can have more than one valencies.

3 0
3 years ago
Read 2 more answers
Hydrogen produced from a hydrolysis reaction was collected over water and the following data was compiled.
Shkiper50 [21]

Answer:

  • 0.00358 mol

Explanation:

<u>1) Data:</u>

a) V = 93.90 ml

b) T = 28°C

c) P₁ = 744 mmHg

d) P₂ = 28.25 mmHg

d) n = ?

<u>2) Conversion of units</u>

a) V = 93.90 ml × 1.000 liter / 1,000 ml = 0.09390 liter

b) T = 28°C = 28 + 273.15 K = 301.15 K

c) P₁ = 744 mmHg × 1 atm / 760 mmHg = 0.9789 atm

d) P₂ = 28.5 mmHg × 1 atm / 760 mmHg = 0.0375 atm

<u>3) Chemical principles and formulae</u>

a) The total pressure of a mixture of gases is equal to the sum of the partial pressures of each gas. Hence, the partical pressure of the hydrogen gas collected is equal to the total pressure less the vapor pressure of water.

b) Ideal gas equation: pV = nRT

<u>4) Solution:</u>

a) Partial pressure of hydrogen gas: 0.9789 atm - 0.0375 atm = 0.9414 atm

b) Moles of hygrogen gas:

pV = nRT ⇒ n = pV / (RT) =

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n = 0.00358 mol (which is rounded to 3 significant figures) ← answer

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