First, you need to find the number of moles of OH⁻ in a 250mL solution of 0.100M OH⁻. To do this, multiply 0.250L by 0.100M to get 0.025mol OH⁻. Then you use the fact that 1 mole of Sr(OH₂)·8H₂O contains 2 moles of OH⁻ which means that 0.0125mol of Sr(OH)₂·8H₂O contains 0.025mol OH⁻ (0.025/2=0.0125). Then to find the amount of Sr(OH)₂·8H₂O is needed you multiply its molar mass (265.76g/mol) by 0.0125mol to get 3.322g.
Therefore you need 3.322g of Sr(OH)₂·8H₂O.
I hope that helps. Let me know if anything is unclear.
Answer
A. It changes the rate, R
Explanation
When we change the concentration of the reactants in a chemical reaction, it affects the rate of reaction that happens in the process. Typically, the rate of reaction will decrease with time if the concentration of the reactants decreases because the reactants will be converted to products. Similarly, the rate of reaction will increase when the concentration of reactants are increased.
Answer:
Option B.
Explanation:
- 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂
First we <u>convert 9.90 g of Pb(NO₃)₂ into moles</u>, using its molar mass:
- 9.90 g ÷ 331.2 g/mol = 0.0299 mol Pb(NO₃)₂
Then we<u> convert moles of Pb(NO₃)₂ into moles of PbO</u>, using the stoichiometric coefficients:
- 0.0299 mol Pb(NO₃)₂ * = 0.0299 mol PbO
Now we<u> convert 0.0299 mol PbO into grams</u>, using its molar mass:
- 0.0299 mol PbO * 223.2 g/mol = 6.67 g PbO
So <em>6.67 g is the theoretical yield</em>. With that in mind <u>we calculate the percent yield</u>:
- % yield = 5.51 / 6.67 * 100 % = 82.6%
So the correct answer is option B.
<span>Petroleum and biomass are burned in combustion reactions, which liberate energy stored in chemical bonds. This is chemical energy. In contrast, nuclear energy comes from the conversion of mass into energy when an nuclear reaction occurs. Geothermal energy comes directly from heat sources underground, with no chemical or nuclear reactions.</span>
Answer:
ʟᴇᴛᴛᴇʀ: ᴄ.
Explanation:
ɪʙᴀ ᴀɴɢ ᴇxᴘʟᴀɴᴀᴛɪᴏɴ sᴀ ʟᴀʜᴀᴛ ɴɢ ᴀɴsᴡᴇʀ