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3 years ago

If there is a New Moon at midnight on October 1, when would the next New Moon occur?

1 answer:

8 0

Answer: C

Explanation: A lunar month is 29.53 earth days. Since an earth calendar as only integer days, it could be either 29 or 30 days later.

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Question List (4 items) (Drag and drop into the appropriate area) Find the volume of HCl that will neutralize the base. Find the

expeople1 [14]

The question is incomplete, the complete question is:

The solubility of slaked lime, $Ca(OH)_2$ , in water is 0.185 g/100 ml. You will need to calculate the volume of $2.50\times 10^{-3}$ M HCl needed to neutralize 14.5 mL of a saturated

Answer: The volume of HCl required is 290mL, the mass of $Ca(OH)_2$ is 0.0268g, the moles of

Explanation:

Given values:

Solubility of $Ca(OH)_2$ = 0.185 g/100 mL

Volume of $Ca(OH)_2$ = 14.5 mL

Using unitary method:

In 100 mL, the mass of $Ca(OH)_2$ present is 0.185 g

So, in 14.5mL. the mass of $Ca(OH)_2$ present will be = $\frac{0.185}{100}\times 14.5=0.0268g$

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

The equation used is:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

Given mass of $Ca(OH)_2$ = 0.0268 g

Molar mass of $Ca(OH)_2$ = 74 g/mol

Plugging values in equation 1:

$\text{Moles of }Ca(OH)_2=\frac{0.0268g}{74g/mol}=0.000362 mol$

Moles of $OH^-$ present = $(2\times 0.000362)=0.000724mol$

The chemical equation for the neutralization of calcium hydroxide and HCl follows:

$Ca(OH)_2+2HCl\rightarrow CaCl_2+2H_2O$

By the stoichiometry of the reaction:

Moles of $OH^-$ = Moles of $H^+$ = 0.000724 mol

The formula used to calculate molarity:

$\text{Molarity of solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (mL)}}$ .....(2)

Moles of HCl = 0.000724 mol

Molarity of HCl = $2.50\times 10^{-3}$

Putting values in equation 2, we get:

$2.50\times 10^{-3}mol=\frac{0.000724\times 1000}{\text{Volume of solution}}\\\\\text{Volume of solution}=\frac{0.000725\times 1000}{2.50\times 10^{-3}}=290mL$

Hence, the volume of HCl required is 290mL, the mass of $Ca(OH)_2$ is 0.0268g, the moles of

5 0

3 years ago

2-butanone is converted into 3-methyl-3-hexanol using a grignard reagent prepared from 1-bromopropane and magnesium metal in thf

Andre45 [30]

Answer:

Here's what I get.

Explanation:

At the end of the reaction you will have a solution of the alcohol in THF.

The microdistillation procedure will vary, depending on the specific apparatus you are using, but here is a typical procedure.

Transfer the solution to a conical vial.
Add a boiling stone.
Attach a Hickman head (shown below) and condenser.
Place the assembly in in the appropriate hole of an aluminium block on top of a hotplate stirrer.
Begin stirring and heating at a low level so the THF (bp 63 °C) can distill slowly.
Use a Pasteur pipet to withdraw the THF as needed.
When all the THF has been removed, raise the temperature of the Al block and distill the alcohol (bp 143 °C).

7 0

3 years ago

Maggie is a member of her school’s environmental club and is interested in recycling. She asks the question, “How does exposure

miv72 [106K]

The best describes on why and how Maggie should change her question to make it a better scientific question is that the question involves giving an opinion about recycling, so it should be changed to rely only on facts. Hope it helps!

8 0

3 years ago

Read 2 more answers

Write the ions present in a solution of K2CO3. Express your answers as chemical formulas separated by a comma. Offset subscripts

meriva

Answer:

K ^+ , CO3 ^2-

Explanation:

The compound is potassium trioxocarbonate(IV).

It contains cation (potassium ion) and acid radical ( trioxocarbonate (IV) ion).

Since K is in group 1 of the periodic table, it loses one electron to form ion i.e K^1. trioxocarbonate IV ion has a charge of 2-.and so the ions of the compound are as shown in the answer above.

8 0

3 years ago

Compare and contrast archaea and bacteria

Nitella [24]

Answer:

Bacteria contain peptidoglycan in the cell wall; archaea do not. The cell membrane in bacteria is a lipid bilayer; in archaea, it can be a lipid bilayer or a monolayer. Bacteria contain fatty acids on the cell membrane, whereas archaea contain phytanyl.

3 0

2 years ago