## anonymous one year ago Pleasse helppp 1.Stacy reads that a 50:50 mixture of methanol and water is best for keeping a car’s radiator from freezing when the temperature goes down to –40°C. Design an experiment to test this finding. You have a –40°C freezer, water, methanol, graduated cylinders to measure volume, several plastic beakers, and a watch at your disposal. Be sure to state your hypothesis, procedure, and any controls in your experiment. What are the dependent and independent variables? Explain the possible results if your hypothesis is true. (Note: Car antifreeze is a mixture of water and another substance

1. anonymous

2. You have 2 m3 of a mineral ore sample. It has a mass of 1 × 104 kg. Calculate the density of the ore sample and express your results in g/cm3 with appropriate scientific notation. Answer:

2. anonymous

1. The data in the table below represent the pressure of a gas when you change the temperature. Plot a graph of the data, using the blank graph provided below. Draw a trend line and calculate its slope. Are the variables related in any way? If so, explain how. What will be the pressure of the gas at 0°C?

3. anonymous

hi: what do you need help in?

4. anonymous

Chemistry

5. anonymous

ok

6. anonymous

about the first question how do you plan to test if the hypothesis is correct?

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8. anonymous

I know a hypothesis is an If and then statement

9. anonymous

Im confused in the question itself. :(

10. anonymous

Ok in this case what is the question that Stacy want to answer

11. anonymous

if methanol and water is best for keeping a car’s radiator from freezing when the temperature goes down to –40°C?

12. anonymous

yes! also she has a 50:50 mixture that she think is the best. then whit this information you can write the hypothesis

13. anonymous

you dont need to use the if, just write a sentence with this information

14. anonymous

If a Methanol and Water is mixed at a 50:50 Ratio, then the mixture will keep the radiator from freezing when the temperature goes down to –40°C?

15. anonymous

thats looks pretty good. That can be your hypothesis. Now you have to think in experiments to prove o disprove that sentence

16. anonymous

Ok -.- The hard part lol

17. anonymous

you have freezer, water, methanol, graduated cylinders to measure volume, several plastic beakers, and a watch at your disposal. What can you do?

18. anonymous

Put Water in one beaker and methanol in the other.

19. anonymous

Im lost from there :(

20. anonymous

Good! that can be your controls, then you can made a 50:50 mix water and alcohol too (that will be the mix that you want to test)

21. anonymous

Ok so im confused about the volume thing

22. anonymous

50:50 is a mix that have the same amount of water and alcohol. per example: 10mL water + 10 mL alcohol = 20 mL of mix or any other volume but both the same

23. anonymous

Oh ok i get it, but what about the watch. And what would be my independent and dependents

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Ok we can organize what we have, we have 3 plastic beakers, one with 20mL of water, other with 20 mL of alcohol, and other with 20 mL of the mix. All of them at room temperature. Now we can put them in the freezer and wait a time, p.e.: 10 min and open the freezer and see what happen with the liquids in the 3 containers We can put them back and wait other 10 min or longer times.

25. anonymous

Independent variable are the one that you fix in the experiment and dependent variables are the ones that result from the measurement of the results depending of the independent variable that you fixed. Do you understand?

26. anonymous

Nope..

27. anonymous

the variables that you have are: the amount of water in the mix or in your controls the amount of alcohol in the mix or in your controls the time to take the mix to freeze

28. anonymous

the temperature of the freezer is not a variable because you will keep the same all the experiment so that is going to be a constant

29. anonymous

Omg Thank you soo much. Chem is so challenging for me

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31. anonymous

did you figure out which ones are the dependent and the independent variables?

32. anonymous

what will be the results if your hypothesis is true?

33. anonymous

Independent: The amount of water in the mix, the amount of alcohol in the mix Dependent: The time to take the mix to freeze Consent: The temperature of the freezer

34. anonymous

Perfect!!!

35. anonymous

The result is that the Mixture of Methanol and Water can keep a car’s radiator from freezing when the temperature goes down to –40°C.

36. anonymous

The result is that the Mixture of Methanol and Water can keep a car’s radiator from freezing when the temperature goes down to –40°C. Because while the beaker with water and the beaker with methanol froze, the one that was mixed did not freeze.

37. anonymous

The beaker with methanol may not freeze at -40C, the melting point of the methanol is -97C. But if you use methanol in the radiator will boil at 64C much lower than water(100C), when you have the mix the boiling and freezing points will change

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39. anonymous

sure

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2. You have 2 m3 of a mineral ore sample. It has a mass of 1 × 104 kg. Calculate the density of the ore sample and express your results in g/cm3 with appropriate scientific notation.

41. anonymous

Ok Density = mass/ volume so bassicaly you have to do a division of the mass by the volume. The difficulty in the problem is that the mass is given in kg and the volume in m3 and the answer has to be in g/cm3 so you have to convert the kg -> g and the m3 -> cm3 are you familiar with unit conversions and conversion factors?

42. anonymous

1 kg = 100g 1m3 = 1 x 10^6 cm3

43. anonymous

Ok im sorry, im back

44. anonymous

I'm familiar with Unit conversion but not factor

45. anonymous

Ok convert the kg -> g and the m3 -> cm3 and do the division mass/volume

46. anonymous

5.3 g

47. anonymous

mass = 1*10^7 grams volume = 2*10^6 cm^3 divide mass/volume

48. anonymous

so its 5

49. anonymous

But can you express your results in g/cm3 with appropriate scientific notation for me cause thats the hard part

50. anonymous

in this case is very simple the answer is just 5 g/cm3

51. anonymous

How to express it in scientific notation

52. anonymous

1. The data in the table below represent the pressure of a gas when you change the temperature. Plot a graph of the data, using the blank graph provided below. Draw a trend line and calculate its slope. Are the variables related in any way? If so, explain how. What will be the pressure of the gas at 0°C? find the intersection of the values and mark a dot in the paper 10C 723 torr, then the next one 25C 763 torr and so on

53. anonymous

that number has only one digit and you dont need to express in scientific notation

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57. anonymous

Sorry for taking so long:( toke me a while to find how to even find a way to put dots and lines on the graph lol

58. anonymous

then divide pressure over volume P/V for each point and calculate the average value. Or you can calculate from the graph. The value has to be similar. To calculate the pressure at 0C just look at the value in the graph where the line cut the pressure axis

59. anonymous

very nice!!!

60. anonymous

Ok i dont get the P/V thing. Wheres the volume?

61. anonymous

sorry, P/T

62. anonymous

Ok Give me a sec to do that calculations:)

63. anonymous

Sorry you have to do a delta choose two temperature and two pressures and do the difference between them, then do the division of P/T to calculate the slope of the line

64. anonymous

Hold On.... Major Brain Crash. Im confused now

65. anonymous

Any two?

66. anonymous

choose two temperatures

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any two

68. anonymous

55/845=15.36 80/900=11.25

69. anonymous

Hold on wait i divided them

70. anonymous

Ok, what you have to do is the difference between the two pressures divided the difference of the two temperatures

71. anonymous

55-845=790 80-900=820

72. anonymous

No, (900-845)/(80-55)

73. anonymous

(900-845)/(80-55) 55/25=2.2

74. anonymous

Yes you can watch this video if you want to know better how to calculate the slope of a line from the graph https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-linear-equations-functions/8th-slope/v/slope-of-a-line

75. anonymous

so 2.2 would be the slop

76. anonymous

W

77. anonymous

Or would i have to do that to all of them

78. anonymous

since this is a straight line any two point will give a similar answer. You can do for all the points and calculate the average if you want o do the job. Or also it can be calculate from the graph

79. anonymous

Thank you so much!!!!!!! You helped me to the max! Can I ask one more question or are you tired of me lol

80. anonymous

ok

81. anonymous

Also am i able to give you owl bucks on here?

82. anonymous

Thank you for the testimonial. I dont have idea about the owl buck I think I have to be a qualified Help and I am not yet.

83. anonymous

Ok Would you like if i close this question then ask another so it can add to your stats?

84. anonymous

ok