"That is a lot to consider."
Translation:Eso es mucho para considerar.
Hmm? 'considerar' is a verb meaning 'to consider'. And this sentence makes us think that '...'to consider' is one in the same as the verb. So I feel that the 'considerar' is being used in a general sense. Therefore we need to use the (to).
We have seen this construction many times. Sometimes we recognized it. Other times not.
So I thought I might as well try some examples.
Eso es mucho para consumir. That is a lot to consume.
Esto es demasiado para comer. This is too much to eat.
Tengo que mucho a hacer. I have much to do.
I hope I'm on the right track here. Creating various sentences sometimes help me understand.
The preposition is not chosen based on the infinitive, it is chosen based on the preceding (conjugated) verb. See: http://www.elearnspanishlanguage.com/grammar/verb/verbswithprep.html
In this (Duo's) sentence, "ser" does not require a preposition between it and the infinitive. It is the quantifier (mucho) (or poco, demasiado, nada) that calls for a preposition between it and the infinitive, although it is the conjugated verb which determines which preposition is used.
Here we have "ser" (es), so the preposition is "para" or "a".
This might help: http://dictionary.reference.com/browse/that
"That" is a complicated little word ><. In the sentence above, it is acting as a pronoun and not an adjective.
As far as I understand it, esa and ese are used for a specific indicated object "ese coche es rojo" but eso is used for more vague concepts like the one above. I'm still not sure though. I think this is a bit like para/por and eventually you just have to learn it by rote and by what feels natural :/
¡Hola! Ryan. Since you have not yet received a response from a hispanohablante, I hope you don't mind if I share an observation.
As you probably know, there are many Spanish verbs that, when followed by an infinitive (or object), require a preposition as a separator. Which preposition is determined by the verb. An example would be verbs of motion, beginning, or learning which require the preposition "a". For example : ir a (+ infinitive), entrar a, llegar a, apprender a, comenzar a, empezar a. A good reference:
Your example "tratar de" does not quite fit this mold because it is a fixed expression (try to), similar to "tener que" (have to).
Duo's sentence does not fit the mold either because it is not the conjugated verb which is calling for the preposition. It seems that when a non-numerical quantifier (such as: mucho, poco, demasiado, nada) is used after the verb and before the infinitive, it is the quantifier that requires the preposition between it and the infinitive, although again it is the verb that determines which preposition is used.
With "ser" the preposition is "para" although "a" seems to be acceptable as well. With "tener" the preposition is "que".
Eso es mucho para considerar. (es mucho para)
Esto es demasiado para comer. (es demasiado para)
Tengo mucho que hacer (tengo mucho que)
Yo tengo poco que añadir ahora. (tengo poco que) I have little to add now.
As I said, an observation, take it with a grain of salt.