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3 years ago

How did geologist find out that the ash in Idaho is the same ash in Nebraska

Chemistry

1 answer:

Zolol [24]3 years ago

3 0

Answer:

Only a volcano could have produced so much ash, but there are NO volcanoes in Nebraska, where the animals were found. One Geologist in Idaho knew of a volcanic eruption dating from the same time.Bill Bonnichsen tied the 2 events together using dating techniques and comparing the ash composition from a supervolcano called Bruneau Jarbridge.

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A volume of 129 mL of hydrogen is collected over water. The water level in the collecting vessel is the same as the outside leve

mixas84 [53]

Explanation:

As it is given that water level is same as outside which means that theoretically, P = 756.0 torr.

So, using ideal gas equation we will calculate the number of moles as follows.

PV = nRT

or, n = $\frac{PV}{RT}$

= $\frac{\frac{756}{760}atm \times 0.129 L}{0.0821 Latm/mol K \times 298 K}$

= 0.0052 mol

Also, No. of moles = $\frac{mass}{\text{molar mass}}$

0.0052 mol = $\frac{mass}{2 g/mol}$

mass = 0.0104 g

As some of the water over which the hydrogen gas has been collected is present in the form of water vapor. Therefore, at $25^{o}C$

$P_{\text{water vapor}}$ = 24 mm Hg

= $\frac{24}{760}$ atm

= 0.03158 atm

Now, P = $\frac{756}{760} - 0.03158$

= 0.963 atm

Hence, n = $\frac{0.963 atm \times 0.129 L}{0.0821 L atm/mol K \times 298 K}$

= 0.0056 mol

So, mass of $H_{2}$ = 0.0056 mol × 2

= 0.01013 g (actual yield)

Therefore, calculate the percentage yield as follows.

Percent yield = $\frac{\text{Actual yield}}{\text{Theoretical yield}} \times 100$

= $\frac{0.01013 g}{0.0104 g} \times 100$

= 97.49%

Thus, we can conclude that the percent yield of hydrogen for the given reaction is 97.49%.

3 0

3 years ago

Write the symbol of another isotope of lead with 132 neutrons.

Ivahew [28]

Answer:

Pb^+7

Explanation:

I placed the carrot there to signify the +7 is supposed to be small. It is plus seven because seven nuetrons are added

5 0

3 years ago

A 0. 1220 g vitamin c tablet was dissolved in acid. This required 11. 50 ml of 0. 01740 m kio3 to reach the endpoint. Calculate

kodGreya [7K]

86.66 % by weight of ascorbic acid in the tablet, when 0. 1220 g vitamin c tablet was dissolved in acid. This required 11. 50 ml of 0. 01740 m $KIO_3$ to reach the endpoint.

<h3>What is a balanced chemical equation?</h3>

A balanced chemical reaction is an equation that has equal numbers of each type of atom on both sides of the arrow.

$3C_6H_80_6 +3I_2 +KIO_3 +5KI +6H^+$ → $3C_6H_60_6 +6I^- +3I_2+6K^+ +3H_2O$

So, the balanced chemical equation for the reaction will be:

$3C_6H_8O_6 +KIO_3$ → $3C_6H_6O_6 +KI + 3H_2O$

That means, 3 mol of of ascorbic acid reacts with 1 mol of $KIO_3$

Moles of $KIO_3$ available is 0.0174 X 0.0115 =0.0002001 mol

Moles of ascorbic acid to be yielded should be 3 X 0.0002001 =0.0006003

So, percent mass of ascorbic acid in the tablet will be:

(0.1057 / 0.1220) X 100 %

=86.66 %

Hence, the third option is the correct answer.

Learn more about balanced chemical equations here:

brainly.com/question/26750249

#SPJ4

8 0

2 years ago

What mass of sodium chloride (NaCl) forms when 7.5 g of sodium carbonate (Na2CO3) reacts with a dilute solution of hydrochloric

Gre4nikov [31]

The mass of NaCl formed is 8.307 grams

<u><em> calculation</em></u>

step 1: write the equation for reaction

Na₂CO₃ + 2HCl → 2 NaCl +CO₂ +H₂O

Step 2: find the moles of Na₂CO₃

moles = mass/molar mass

The molar mass of Na₂CO₃ is = (23 x2) + 12 + ( 16 x3) = 106 g/mol

moles = 7.5 g/106 g/mol =0.071 moles

Step 3: use the mole ratio to determine the mole of NaCl

Na₂CO₃:NaCl is 1:2 therefore the moles of NaCl =0.07 x2 =0.142 moles

Step 4: calculate mass of NaCl

mass= moles x molar mass

the molar mass of NaCl= 23 +35.5 =58.5 g/mol

mass = 0.142 moles x 58.5 g/mol =8.307 grams

8 0

3 years ago

Read 2 more answers

The protein lysozyme unfolds at a transition temperature of 75.5°C, and the standard enthalpy of transition is 509 kJ mol-1. Cal

spin [16.1K]

Answer:

0.4774 KJ/K.mol

Explanation:

We are told that the transition at 25.0°C occurs in three steps. Steps i, ii and iii.

Thus;

the entropy of unfolding of lysozyme = ΔS_i + ΔS_ii + ΔS_iii

Now,

C_p,m(unfolded protein) = C_p,m(folded protein) + 6.28 kJ/K.mol

Now, for the first process, ΔS_i is given as;

ΔS_i = C_p,m × In(T2/T1)

We are given;

T1 = 25°C = 25 + 273.15K = 298.15 K

T2 = 75.5°C = 75.5 + 273.15 K=348.65 K

Thus;

ΔS_i = C_p,m × In(348.65/298.15)

Now, for the third process, ΔS_iii is given as;

ΔS_iii = (C_p,m + 6.28 kJ/K.mol) × In(T1/T2)

Thus;

ΔS_iii = (C_p,m + 6.28 kJ/K.mol) × In(298.15/348.65)

Now, we don't know C_pm. So, we have to find a way to eliminate it. We will do it by rewriting In(298.15/348.65) in such a way that when ΔS_iii is added to ΔS_i, C_p,m will cancel out. Thus;

In(298.15/348.65) can also be written as;

In(348.65/298.15)^(-1) or

- In(348.65/298.15)

Thus;

ΔS_iii = - [(C_p,m + 6.28 kJ/K.mol) × In(298.15/348.65)]

Now, let's add ΔS_iii to ΔS_i to get;

ΔS_i + ΔS_iii = [C_p,m × In(348.65/298.15)] + [(-C_p,m - 6.28 kJ/K.mol) × In(348.65/298.15)]

ΔS_i + ΔS_iii = [C_p,m × In(348.65/298.15)] - [C_p,m × In(348.65/298.15)] - [6.28In(348.65/298.15)]

First 2 terms will cancel out to give;

ΔS_i + ΔS_iii = -6.28In(348.65/298.15)

ΔS_i + ΔS_iii = -0.9826 KJ/K.mol

Now,for process ii;

ΔS_ii = standard enthalpy of transition/Transition Temperature

Thus;

ΔS_ii = (509 KJ/K.mol)/348.65

ΔS_ii = 1.46 KJ/K.mol

Thus;

the entropy of unfolding of lysozyme = ΔS_i + ΔS_ii + ΔS_iii = -0.9826 + 1.46 = 0.4774 KJ/K.mol

5 0

3 years ago