Which statements correctly describe thermal energy in a block of ice, a glass of liquid water, and a container of steam?

A football is inflated to 12psi at 20°C What is the new pressure in the football

Radda [10]

Answer: The new pressure is 3 psi.

Explanation:

Given: $P_{1}$ = 12 psi, $T_{1} = 20^{o}C$

$P_{2}$ = ?, $T_{2} = 5^{o}C$

Formula used is as follows.

$\frac{P_{1}}{T_{1}} = \frac{P_{2}}{T_{2}}\\\frac{12 psi}{20^{o}C} = \frac{P_{2}}{5^{o}C}\\P_{2} = \frac{12 psi \times 5^{o}C}{20^{o}C}\\= 3 psi$

Thus, we can conclude that the new pressure is 3 psi.

7 0

3 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

3 years ago

Which of the following pieces of laboratory glassware should be used to most accurately measure out a 25.00 ml sample of a solut

wel

Answer:

The correct answer is 25 mL graduated cylinder (it should be used in all the cases)

Explanation:

In order to measure 25.00 ml sample of a solution it should be used a 25 mL graduated cylinder, as it is previously and properly calibrated. The other laboratory glassware, beaker and erlenmeyer, have graduations which are approximate, so they are used when exact volumes are not needed.

ii) graduated cylinder has the least uncertainly. It is more accurate than a beaker or erlenmeyer (to within 1%)

iii) A 25 mL graduated cylinder should be used because it is the most accurate lab glassware (between those were mentioned: beaker, erlenmeyer).

6 0

3 years ago

A chemist sets up a chemical reaction but finds that none of the reactant molecules have a required activation energy. What is t

Anvisha [2.4K]

Activation energy is the minimum amount of energy that the colliding reactant molecules must possess for the formation of products. Lower the activation energy, higher will be chance of formation of products. So activation energy is the minimum energy requirement that has to overcome for the reaction to be completed. Therefore, when in a chemical reaction the reactant molecules do not collide with required activation energy, the collisions will not be fruitful even if they are properly oriented which means that the products will not form.

Hence the correct answer will be B.) no products will be formed

5 0

3 years ago

Read 2 more answers

What period is the atom in?

lys-0071 [83]

It is in period 3
It is in group 17
It is a chlorine atom because it has 17 electrons which means the atomic number is 17

6 0

3 years ago