In the haber process for the production of ammonia, what is the relationship between the rate of production of ammonia and the rate of consumption of hydrogen?
n2(g) + 3 h2(g) -> 2 nh3(g)

answer choices
a.) δ[nh3] / δt = −3/2 δ [h2] / δt
b.) δ[nh3] / δt = δ [h2] / δt
c.) 3/2 δ[nh3] / δt = δ [h2] / δt
d.) δ[nh3] / δt = −2/3 δ [h2] / δt
e.) δ[nh3] / δt = 2/3 δ [h2] / δt
f.) 2/3 δ[nh3] / δt = −δ [h2] / δt

Δ[NH₃]/Δt  = 2/3 ( Δ[H₂]/Δt )

Explanation:

For determining rates as a function of reaction coefficients one should realize that these type problems are always in pairs of reaction components. For the reaction N₂ + 3H₂ => 2NH₃ one can compare ...

Δ[N₂]/Δt  ∝ Δ[H₂]/Δt, or

Δ[N₂]/Δt  ∝ Δ[NH₃]/Δt, or

Δ[H₂]/Δt  ∝ Δ[NH₃]/Δt, but never 3 at a time.

So, set up the relationship of interest ( ammonia rate vs. hydrogen rate)... nitrogen rate is ignored.

Δ[H₂]/Δt  ∝ Δ[NH₃]/Δt

Now, 'swap' coefficients of balanced equation and apply to terms given then set term multiples equal ...

N₂ + 3H₂ => 2NH₃   => 2(Δ[H₂]/Δt)  = 3(Δ[NH₃]/Δt) => 2/3(Δ[H₂]/Δt)  = (Δ[NH₃]/Δt)

NOTE => Comparing rates individually of the component rates in reaction process, the rate of H₂(g) consumption is 3/2 times faster than NH₃(g) production (larger coefficient).  So, in order to compose an equivalent mathematical relationship between the two, one must reduce the rate of the H₂(g) by 2/3 in order to equal the rate of NH₃(g) production. Now, given the rate of one of the components as a given, substitute and solve for the unknown.

CAUTION => When Interpreting rate of reaction one should note that the  rate expression for an individual reaction component defines 'instantaneous' rate or speed. This means velocity (or, speed) does not have 'signage'. Yes, one may say the rate is higher or lower as time changes but that change is an acceleration or deceleration for one instantaneous velocity to another. Acceleration and Deceleration do have signage but the positional instantaneous velocity (defined by a point in time) does not. Thus is reason for the  'e-choice' answer selection without the signage associated with the expression terms.  

hi,

the answer is d, it has indefinite shape but definite volume.

hope this !

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what keeps bread soft is the moisture retained in the crumb (the light spongy part that’s not crust). the reason the crust develops is the surface of the dough gets exposed to hot dry air during baking which browns the outer layer and seals it, preventing all the moisture from escaping the dough. longer exposure to air will also eventually cause your bread to lose flavor and become stale.

people were used to cutting slices as they needed them and storing bread in a specially-made wooden or metal breadbox or pail with a lid to preserve it longer, but the first automatically sliced commercial loaves were produced on july 6, 1928, in chillicothe, missouri, using a machine invented by otto rohwedder, an iowa-born, missouri-based jeweler.[1] pre-sliced bread would indeed dry out, were it not for another 20th century technology: the plastic bag. bread could now be pre-sliced, and if the enclosing bag remains sealed as much as possible, the bread will remain soft and fresh for longer than if sitting unwrapped on a shelf or enclosed in a bread box that is not air-tight. sealed packaging meant bread could also be sold on store shelves and eliminate frequent trips to a bakery.

sealing bread in a plastic bag had another effect: the moisture in the loaf will re-distribute into the crust and soften it, which is sometimes more pleasing in a sandwich - especially for children whose teeth might not yet be strong enough to tear through a hard crust. a homemade loaf of bread can be sealed in a bag overnight and the crust will become soft like store-bought sandwich bread.

these were novel changes in how bread was produced and sold, which led to the coining of the phrase “the greatest thing since sliced bread.”