How many grams of water are needed to add to 4.00 grams NaOH to create a 2.00% solution

The answer to your question is 200 g

Explanation:

Data

mass of water = ?

mass of NaOH = 4 g

concentration = 2 %

Formula

  % mass = mass of solute/mass of solution x 100

-Solve for mass of solution

  mass of solution = mass of solute / % mass x 100

-Substitution

  mass of solution = 4 / 2 x 100

-Simplification

  mass of solution = 2 x 100

-Result

  mass of solution = 200 g

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.