TRUE OR FALSE? The genetic code is determined by the SIZES of the nitrogen bases.

The highly exothermic thermite reaction, in which aluminum reduces iron(iii) oxide to elemental iron, has been used by railroad

JulijaS [17]

To illustrate clearly, I will rewrite the reaction in a more understandable manner.

2 Al(s) + Fe₂O₃ (s) ⇒ 2 Fe(s) + Al₂O₃(s) Δhrxn = –850 kJ

This reaction has a negative sign for the change in enthalpy of reaction. The sign convention only means that the reaction releases energy to the surroundings. In other words, the reaction is exothermic. Focusing on only its magnitude, this means that 850 kJ of energy is needed for this reaction of 2 Aluminum moles and 1 mole of Fe₂O₃ to occur.

Now, if you only had an energy of 725 kJ, then the reaction is incomplete but it will still form Iron (Fe). We use stoichiometric calculations as follows:

725 kJ * (2 mol Fe/850 kJ) = 1.7 moles of Fe

Knowing that the molar mass of Fe is 55.6 g/mol, then the mass of produced iron is

1.7 mol Fe * 55.6 g/mol = 94.85 g iron

6 0

3 years ago

A bicycle tire is spinning counterclockwise at 2.70 rad/s. During a time period At 1.90 s, the tire is stopped and spun in the o

Naddik [55]

Answer:

a) -5.40 rad/s

b) -2.842 rad/s²

Explanation:

The direction is important in dealing with such questions. Clockwise is considered negative and counterclockwise is considered positive

a) Δω = final angular velocity - initial angular velocity

= -2.70 rad/s - 2.70 rad/s

= -5.40 rad/s

b) ∝ = Δω/Δt = (-5.40 rad/s)/1.90s = -2.842 rad/s²

7 0

3 years ago

Which best describes emerging scientific ideas?

natka813 [3]

Following both the statements are true:
Some Defined it by
"Supported by most but not all".
Some defined it by this statement:
"Not studied by many scientists"

7 0

3 years ago

To keep the calculations fairly simple, but still reasonable, we shall model a human leg that is 92.0 cm long (measured from the

lorasvet [3.4K]

Answer:

Xc = 64.27 cm, Yc = 0 cm, Xc = 27.73 cm, Yc = 18.27 cm

Explanation:

A human leg is 92 cm long equally divided into two parts (upper leg and lower leg) that is both are 46 cm long

M1 = 8.35 kg

M2 = 5.50 kg

A. Starting from hip joint, when the leg is placed horizontally, the X coordinate of centre of mass will be

Xc = (m1x1 + m2x2) / m1 + m2

Xc = (8.35x46 + 5.50 x 92) / 8.35 + 5.50

( here we took x2 = 92 cm because we are measuring length from the hip joint, that means length at hip joint is 0 and at the foot 92 cm)

Xc = 890.1 / 13.85

Xc = 64.27 cm

B. Yc = (y1m1 + y2m2) / m1 + m2

Yc = (0x8.35 + 0x5.50) / 8.35 + 5.50

( here y1 and y2 are 0 because the leg is placed horizontally that means in X direction so none of the leg component is in Y direction)

Yc = 0 cm

C. Xc = (m1x1 + m2x2) / m1 + m2

Xc = (8.35x46 + 5.50x0) / 8.35 + 5.50

(here x2 is taken 0 because the other half leg is bent vertically that means it is in Y direction so its X component is 0)

Xc = 384.1 / 13.85

Xc = 27.73 cm

D. Yc = (m1y1 + m2y2) / m1 + m2

Yc = (8.35x0 + 5.50x46) / 8.35 + 5.50

(here y1 is zero because the upper leg is in X direction and y2 is taken 46 cm because starting measuring from hip joint 46 cm of length of lower leg is in Y direction)

Yc = 253/13.85

Yc = 18.27 cm

7 0

3 years ago

Without electrons atoms would carry A. no charge at all. B. a positive charge. C. a negative charge. D. an alternating charge.

kykrilka [37]

Answer is B A positive charge

5 0

3 years ago