Answer:
69.7 mL ≅ 70 mL
Explanation:
The chemical reaction between hydrobromic acid (HBr) and lithium metal (Li) produces lithium bromide (LiBr) and hydrogen (H₂) according to the following equation:
2HBr(aq) + 2Li(s) → 2LiBr(aq) + H₂(g)
Thus, 2 moles of HBr reacts with 2 moles of Li. So, the stoichiometric ratio is 1:1 (1 mol HBr reacts with 1 mol Li).
We convert the mass of Li to moles by using the molar mass (MM) of LiBr:
MM(LiBr) = 6.9 g/mol + 79.9 g/mol = 86.8 g/mol
moles of Li(s) = mass/MM(LiBr) = 19.4 g/86.8 g/mol = 0.223 moles Li(s)
Now, we can divide the moles of Li into the molarity of the HBr solution to obtain the volume in liters wee need to add:
V = moles Li(s)/M = (0.223 mol)/(3.2 mol/L) = 0.0697 L
0.0697 L x 1000 mL/1 L = 69.7 mL ≅ 70 mL
Therefore, 70 mL of 3.2 M HBr are needed to entirely dissolve the metal.
#2 It gives out more energy :)
Answer:
Independent Variable: The thing in an experiment which is changed.
Dependent Variable: The thing in an experiment which is affected by the change. (In other words, it's affected by the independent variable.)
Control Variable: The other factors of the experiment that remain unchanged.
For example, say you want to do an experiment about the effects of water on plant height. So, the independent variable, or the thing that is changed would be the amount of water, and the dependent variable would be the plant height, as the plant height is directly affected by the independent variable. Lastly, for this to be a fair experiment, there must be control variables. For example, all of the plants should be put in a room with equal temperature, they should get the same amount of sunlight, etc.
I hope this answers your question- feel free to ask me if you need any more help.
Answer:
Ca2+ represents an ion with 20 protons and 18 electrons.
Explanation:
A calcium atom has 20 protons and 20 electrons. The 2+ charge next to the symbol indicates a loss of two electrons: 20-2=18.
Answer:
0.0827M of H₂SO₃
Explanation:
LiOH reacts with H₂SO₃ to produce water and Li₂SO₃, thus:
2LiOH + H₂SO₃ → 2H₂O + Li₂SO₃
<em>Where 2 moles of lithium hydroxide react with 1 mole of sulfurous acid.</em>
As the chemist requires 22.14mL = 0.02214L of a 0.210M solution to neutralize the acid, moles of LiOH are:
0.02214L × (0.210mol / L) =<em>0.004649 moles of LiOH</em>.
As 2 moles of LiOH react with 1 mole of H₂SO₃, moles of H₂SO₃ are:
0.004649 moles of LiOH ₓ (1 mole H₂SO₃ / 2 mol LiOH) =
<em>0.002325 moles of H₂SO₃</em>
These moles are present in 28.10mL = 0.02810L. Thus, molar concentration of the acid is:
0.002325 moles H₂SO₃ / 0.02810L = <em>0.0827M of H₂SO₃</em>