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2 years ago

5. Mr. Martin's Spanish class is 45 minutes long. If it starts at 3:30, what time does it end?

Chemistry

2 answers:

zubka84 [21]2 years ago

5 0

It would be 4:15 . Just add 3:30 plus 45 too get the answer

butalik [34]2 years ago

3 0

It ends at 4:15
hope it helps!

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Draw a Lewis structure for ketene, C2H2O , which has a carbon‑carbon double bond. Include all hydrogen atoms and show all unshar

Vladimir79 [104]

Answer: The lewis dot structure is attached below.

Explanation:

A Lewis dot structure is defined as the representation of atoms having electrons around the atom where electrons are represented as dots.

A ketene is an organic compound having general formula R′R″C=C=O, where R and R' are two different/same monovalent chemical groups.

The given chemical compound having formula $C_2H_2O$ is represented as $H_2-C=C=O$ .

Total number of unshared electrons = 4 (left on oxygen atom only)

The lewis dot structure of $C_2H_2O$ is given in the image below.

8 0

2 years ago

A student mixes 33.0 mL of 2.70 M Pb ( NO 3 ) 2 ( aq ) with 20.0 mL of 0.00157 M NaI ( aq ) . How many moles of PbI 2 ( s ) prec

GalinKa [24]

Answer: The moles of precipitate (lead (II) iodide) produced is $1.57\times 10^{-5}$ moles

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$ .....(1)

For lead (II) nitrate:

Molarity of lead (II) nitrate solution = 2.70 M

Volume of solution = 33.0 mL = 0.033 L (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

$2.70M=\frac{\text{Moles of lead (II) nitrate}}{0.033L}\\\\\text{Moles of lead (II) nitrate}=(2.70mol/L\times 0.0330L)=0.0891mol$

For NaI:

Molarity of NaI solution = 0.00157 M

Volume of solution = 20.0 mL = 0.020 L

Putting values in equation 1, we get:

$0.00157M=\frac{\text{Moles of NaI}}{0.020L}\\\\\text{Moles of NaI}=(0.00157mol/L\times 0.0200L)=3.14\times 10^{-5}mol$

For the given chemical reaction:

$Pb(NO_3)_2(aq.)+2NaI(aq.)\rightarrow PbI_2(s)+2NaNO_3(aq.)$

By Stoichiometry of the reaction:

2 moles of NaI reacts with 1 mole of lead (II) nitrate

So, $3.14\times 10^{-5}$ moles of NaI will react with = $\frac{1}{2}\times 3.14\times 10^{-5}=1.57\times 10^{-5}mol$ of lead (II) nitrate

As, given amount of lead (II) nitrate is more than the required amount. So, it is considered as an excess reagent.

Thus, NaI is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

2 moles of NaI produces 1 mole of lead (II) iodide

So, $3.14\times 10^{-5}$ moles of NaI will produce = $\frac{1}{2}\times 3.14\times 10^{-5}=1.57\times 10^{-5}moles$ of lead (II) iodide

Hence, the moles of precipitate (lead (II) iodide) produced is $1.57\times 10^{-5}$ moles

4 0

2 years ago

Draw the other possible resonance structure of each organic ion. In each case, draw the structure that minimizes formal charges.

pshichka [43]

Three resonance structures can be drawn for the allyl cation while two resonance structures can be drawn for the amidate ion.

Sometimes, we cannot fully describe the bonding in a chemical specie using a single chemical structure. In such cases, we have to use a number of structures which cooperatively represent the actual bonding in the molecule. These structures are called resonance or canonical structures.

The resonance structures of the allyl cation and the amidate ion are shown in the images attached to this answer. These structures show the different bonding extremes in these organic ions.

Learn more: brainly.com/question/4933048

7 0

2 years ago

199.5 grams unrefined dark crystalline sugar to cups

Dmitry [639]

Answer:

0.9975 cup

Step-by-step explanation:

"Unrefined dark crystalline sugar" is what non-chemists call "brown sugar."

200.0 g brown sugar = 1 cup

199.5 g brown sugar = 199.5× 1/200 .0

199.5 g brown sugar = 0.9975 cup

A standard measuring cup is not capable of this precision and, furthermore, the mass of brown sugar you can get into a cup depends on how tightly you pack it.

Your Mole Day cake will be fine if you use 1 cup of brown sugar as usual.

4 0

3 years ago

Help please I don’t understand this at all

Paladinen [302]

I think you must do dot and cross diagrams but im not sure at all

7 0

2 years ago

Read 2 more answers