Someone help me with these problems concerning mass, volume, and density?

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1. A Fertilizer contains 21% nitrogen by mass. What mass of this fertilizer, in kgs, is required for an application requiring 775 g of nitrogen?

2. Calculate the mass of a block of iron (p= 7.86 g/mL) with dimensions 52.8 cm x 6.74 cm x 3.73 cm.

3. The density of aluminum is 2.70 g/cm^(3). A square piece of aluminum foil, 9.0 inch on a side, is found to weigh 2.568 g. What is the thickness of this foil, in milliliters?

4. A recipe for roasting a cut of meat is 350*F. What is the temperature on the Celsius scale?

THANKS. 🙂

please show the complete solution. i’m not good at this so please help me. i want to learn how. thank you. 🙂

2 Answers

  1. 1. let mass of fertilizer be m

    775= 21% of m

    775 = 21/100 * m

    3690 g = m

    2. mass = density * volume

    mass = 7.86 * 52.8 * 6.74 * 3.73 …………….. (since 1ml = 1 cm^3)

    mass = 11872 ( approx) = 1.18 * 10^3 ( approx) ……………. (3 significant figure)

    3. volume = mass/density

    volume = 2.568 / 2.70

    volume = 0.95 cm^3 ( approx)

    1 inch = 3 cm

    thus 9 inch = 27 cm

    thus 27^2 * thickness = 0.95

    thickness = 0.001 cm

    4. (c*9/5) +32 = f

    c = Celsius f = Fahrenheit

    c = (f-32) *5/9

    c = (350- 32) * 5/9

    c = 318* 5/9

    c = 176.66

    : )

  2. 1)

    0.21x = 775

    x = 775/0.21

    x = 3690.47 g

    2)

    52.8 cm x 6.74 cm x 3.73 cm = 1327.40256 cm^3

    > 1 Cubic Centimeter = 1 Milliliter <

    1327.40256 cm^3 = 1327.40256 mL

    1327.40256 mL * 7.86 g/mL = 10433.38 g

    Get the idea? You can do the other two.

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