Which best describes a scientist who solves a new problem using something already learned?
creative
curious
observant
skeptical

Answer:

3) About 0.35 grams of hydrogen gas.

4) About 65.2 grams of aluminum oxide.

Explanation:

Question 3)

We are given that 7.9 grams of sodium is dropped into a bathtub of water, and we want to determine how many grams of hydrogen gas is released.

Since sodium is higher than hydrogen on the activity series, sodium will replace hydrogen in a single-replacement reaction for sodium oxide. Hence, our equation is:

[tex]\displaystyle \text{Na} + \text{H$_2$O}\rightarrow \text{Na$_2$O}+\text{H$_2$}[/tex]

To balance it, we can simply add another sodium atom on the left. Hence:

[tex]\displaystyle 2\text{Na} + \text{H$_2$O}\rightarrow \text{Na$_2$O}+\text{H$_2$}[/tex]

To convert from grams of sodium to grams of hydrogen gas, we can convert from sodium to moles of sodium, use the mole ratios to find moles in hydrogen gas, and then use hydrogen's molar mass to find its amount in grams.

The molar mass of sodium is 22.990 g/mol. Hence:

[tex]\displaystyle \frac{1\text{ mol Na}}{22.990 \text{ g Na}}[/tex]

From the chemical equation, we can see that two moles of sodium produce one mole of hydrogen gas. Hence:

[tex]\displaystyle \frac{1\text{ mol H$_2$}}{2\text{ mol Na}}[/tex]

And the molar mass of hydrogen gas is 2.016 g/mol. Hence:

[tex]\displaystyle \frac{2.016\text{ g H$_2$}}{1\text{ mol H$_2$}}[/tex]

Given the initial value and the above ratios, this yields:

[tex]\displaystyle 7.9\text{ g Na}\cdot \displaystyle \frac{1\text{ mol Na}}{22.990 \text{ g Na}}\cdot \displaystyle \frac{1\text{ mol H$_2$}}{2\text{ mol Na}}\cdot \displaystyle \frac{2.016\text{ g H$_2$}}{1\text{ mol H$_2$}}[/tex]

Cancel like units:

[tex]=\displaystyle 7.9\cdot \displaystyle \frac{1}{22.990}\cdot \displaystyle \frac{1}{2}\cdot \displaystyle \frac{2.016\text{ g H$_2$}}{1}[/tex]

Multiply. Hence:

[tex]=0.3463...\text{ g H$_2$}[/tex]

Since we should have two significant values:

[tex]=0.35\text{ g H$_2$}[/tex]

So, about 0.35 grams of hydrogen gas will be released.

Question 4)

Excess oxygen gas is added to 34.5 grams of aluminum and produces aluminum oxide. Hence, our chemical equation is:

[tex]\displaystyle \text{O$_2$} + \text{Al} \rightarrow \text{Al$_2$O$_3$}[/tex]

To balance this, we can place a three in front of the oxygen, four in front of aluminum, and two in front of aluminum oxide. Hence:

[tex]\displaystyle3\text{O$_2$} + 4\text{Al} \rightarrow 2\text{Al$_2$O$_3$}[/tex]

To convert from grams of aluminum to grams of aluminum oxide, we can convert aluminum to moles, use the mole ratios to find the moles of aluminum oxide, and then use its molar mass to determine the amount of grams.

The molar mass of aluminum is 26.982 g/mol. Thus:

[tex]\displaystyle \frac{1\text{ mol Al}}{26.982 \text{ g Al}}[/tex]

According to the equation, four moles of aluminum produces two moles of aluminum oxide. Hence:

[tex]\displaystyle \frac{2\text{ mol Al$_2$O$_3$}}{4\text{ mol Al}}[/tex]

And the molar mass of aluminum oxide is 101.961 g/mol. Hence: [tex]\displaystyle \frac{101.961\text{ g Al$_2$O$_3$}}{1\text{ mol Al$_2$O$_3$}}[/tex]

Using the given value and the above ratios, we acquire:

[tex]\displaystyle 34.5\text{ g Al}\cdot \displaystyle \frac{1\text{ mol Al}}{26.982 \text{ g Al}}\cdot \displaystyle \frac{2\text{ mol Al$_2$O$_3$}}{4\text{ mol Al}}\cdot \displaystyle \frac{101.961\text{ g Al$_2$O$_3$}}{1\text{ mol Al$_2$O$_3$}}[/tex]

Cancel like units:

[tex]\displaystyle= \displaystyle 34.5\cdot \displaystyle \frac{1}{26.982}\cdot \displaystyle \frac{2}{4}\cdot \displaystyle \frac{101.961\text{ g Al$_2$O$_3$}}{1}[/tex]

Multiply:

[tex]\displaystyle = 65.1852... \text{ g Al$_2$O$_3$}[/tex]

Since the resulting value should have three significant figures:

[tex]\displaystyle = 65.2 \text{ g Al$_2$O$_3$}[/tex]

So, approximately 65.2 grams of aluminum oxide is produced.

Answer:

Solution given:

3.

[tex]2Na+H_2O→Na _2O+H_2[/tex]

2Na=2*23g.

2O=18g.

[tex]Na_2O[/tex]=62g

[tex]H_2[/tex]=2 g

we have

2*23g of Na produce 2g of [tex]H_2[/tex]

Now

7.9 g of Na produce 2*7.9/(2*23)

=0.34g of [tex]H_2[/tex]

4.

we have

[tex]3O_2+4Al→2Al_2O_3[/tex]

[tex]3O_2[/tex]=3*16g*2g

4Al=4*27g

[tex]2Al_2O[/tex]= 2*27*2g+2*16*3g

4*27g of Al produces 204g of [tex]Al_2O_3[/tex]

34.5g of Al produces 204g*34.5/(4*27)

Answer:

15.0 g

Explanation:

15.0% =0.150

100.0 g × 0.150= 15.0g

Sodium nitrate is "an inorganic compound with the formula of NaNO₃.

Inorganic compound is "a chemical compound that lacks carbon–hydrogen bonds".

15% = 0.15

100.0 g × 0.15= 15g

Hence, 15g of Sodium nitrate are needed to prepare 100 gms of a 15% by mass sodium nitrate.

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Answer:

5.25 moles of protons. Option e

Explanation:

Reaction between phosphoric acid and sodium hydroxide is neutralization.

We can also say, we have an acid base equilibrium right here:

H₃PO₄  +  3NaOH →  Na₃PO₄  +  3H₂O

Initially we have 5.25 moles of base.

We have data from the acid, to state its moles:

M = mol/L, so mol = M . L

mol = 1.75 moles of acid

If we think in the acid we know:

H₃PO₄  →  3H⁺  +  PO₄⁻³

We know that 1 mol of acid can give 3 moles of protons (hydrogen ions)

If we have 1.75 moles of acid, we may have

(1.75 . 3) /1 = 5.25 moles of protons

These moles will be neutralized by the 5.25 moles of base

H₃O⁺  +  OH⁻  ⇄  2H₂O     Kw

In a titration of a weak acid and a strong base, we have a basic pH

Answer:

725.15 L

Explanation:

The balanced chemical equation for the reaction between Na₂O₂ and CO₂ is the following:

Na₂O₂ + CO₂ → Na₂CO₃ + 1/2 O₂

From the stoichiometry of the reaction, 1 mol of Na₂O₂ reacts with 1 mol CO₂. So, the stoichiometric ratio is 1 mol Na₂O₂/1 CO₂.

Now, we convert the mass of reactants to moles by using the molecular weight (Mw) of each compound:

Mw (Na₂O₂) = (23 g/mol x 2) + (16 g/mol x 2) = 78 g/mol

moles Na₂O₂ = 96.7 g/(78 g/mol) = 1.24 mol Na₂O₂

Mw (CO₂) = 12 g/mol + (16 g/mol x 2) = 44 g/mol

moles CO₂ = 0.0755 g/(44 g/mol) = 1.71 x 10⁻³ mol CO₂

Now, we calculate the number of moles of CO₂ we need to completely react with the mass of Na₂O₂ we have:

1.24 mol Na₂O₂ x 1 mol CO₂/1 mol Na₂O₂ = 1.24 mol CO₂

In 1 L of respired air we have 1.71 x 10⁻³ mol CO₂ (0.0755 g), so we need the following number of liters to have 1.24 mol of CO₂:

1.24 mol CO₂ x 1 L/1.71 x 10⁻³ mol CO₂ = 725.15 L

Answer:

Theoretical yield of 1-Phenyl-1-propanol in grams = 0.871 g

Explanation:

A Grignard reagent is any of the numerous organic derivatives of magnesium (Mg) which are commonly represented by the general formula RMgX (where R is a hydrocarbon radical e.g. methyl, ethyl, propyl, etc.; and X is a halogen atom, e.g. chlorine, bromine, or iodine)

A Grignard reaction converts an aldehyde to a secondary alcohol. In the grignard reaction involving benzaldehyde as in this experiment, the grignard reagent used is ethyl magnesium bromide, EtMgBr, and the resulting product is 1-Phenyl-1-propanol, a secondary alcohol. The reaction is shown in the figure attached below.

Mass of benzaldehyde in 0.650 mL = density × volume

Density of Benzaldehyde = 1.044 g/mL

Mass of benzaldehyde = 1.044 g/mL × 0.650 mL = 0.6786 g

Molar mass of benzaldehyde = 106 g/mol

Molar mass of 1-Phenyl-1-propanol = 136 g/mol

Mass of = mass of benzaldehyde × mole ratio of 1-Phenyl-1-propanol and benzaldehyde

Mass of 1-Phenyl-1-propanol = 0.6786 g × (136 g/mol)/(106 g/mol) = 0.871 g

Therefore, the theoretical yield of 1-Phenyl-1-propanol in grams = 0.871 g

Answer:

5×6.02×1023

Explanation:

there are 5×6.02×1023 molecules of p4010 in 5mole. there are four P atoms in a single molecule of p4010

Answer:

Average speed of helium is higher than argon.

Explanation:

The average speed of helium is higher than argon atom under the conditions specified because of lower mass of the helium atom as compared to argon atom. Average speed of an atom is inversely proportional to mass of the atom. If mass of an atom decreases, the atom moves with higher speed while on the other hand, if the mass of an atom increases the average speed of an atom decreases.

Answer:

The mass of silver carbonate precipitated is 5.18 grams.

Explanation:

Molarity of the silver nitrate solution = 0.671 M

Volume of the silver nitrate solution = 56.0 mL

[tex]1 mL = 0.001 L\\56.0 mL = 56.0\times 0.001 L=0.0560 L[/tex]

Moles of silver nitrate = n

[tex]Molarity=\frac{\text{Moles of compound}}{\text{Volume of solution in Liters}}\\\\0.671 M=\frac{n}{0.0560 L}\\n=0.671 M\times 0.0560 L=0.0376 mol[/tex]

Moles of silver nitrate used = 0.0376 mol

[tex]K_2CO_3+2AgNO_3\rightarrow Ag_2CO_3+2KNO_3[/tex]

According to the reaction, 2 moles of silver nitrate gives 1 mole of silver carbonate, then 0.0376 moles of silver nitrate:

[tex]=\frac{1}{2}\times 0.0376 mol=0.0188 \text{mol of }Ag_2CO_3[/tex]

Moles of the silver carbonate formed = 0.0188 mol

Molar mass of silver carbonate = 275.7453 g/mol

Mass of silver carbonate :

[tex]=275.7453 g/mol\times 0.0188 mol=5.1840 g\approx 5.18 g[/tex]

The mass of silver carbonate precipitated is 5.18 grams.

Answer:

Likely [tex]\rm In[/tex] (indium.)

Explanation:

Number of atoms: [tex]N = 2.241 \times 10^{21}[/tex].

Dividing, [tex]N[/tex], the number of atoms by the Avogadro constant, [tex]N_A \approx 6.023 \times 10^{23} \; \rm mol^{-1}[/tex], would give the number of moles of atoms in this sample:

[tex]\begin{aligned} n &= \frac{N}{N_{A}} \\ &\approx \frac{2.241 \times 10^{21}}{6.023 \times 10^{23}\; \rm mol^{-1}} \approx 3.72 \times 10^{-3}\; \rm mol \end{aligned}[/tex].

The mass of that many atom is [tex]m = 0.4272\; \rm g[/tex]. Estimate the average mass of one mole of atoms in this sample:

[tex]\begin{aligned}M &= \frac{m}{n} \\ &\approx \frac{0.4272\; \rm g}{3.72 \times 10^{-3}\; \rm mol} \approx 114.82\; \rm g \cdot mol^{-1}\end{aligned}[/tex].

The average mass of one mole of atoms of an element ([tex]114.82\; \rm g \cdot mol^{-1}[/tex] in this example) is numerically equal to the average atomic mass of that element. Refer to a modern periodic table and look for the element with average atomic mass [tex]114.82[/tex]. Indium, [tex]\rm In[/tex], is the closest match.

The symbol of the element is In

From the question, we are to determine the identity of the element

First, we will determine the number of moles of sample present

Using the formula

[tex]Number \ of\ moles = \frac{Number\ of \ atoms }{Avogadro's\ constant}[/tex]

Number of moles of the sample = [tex]\frac{2.241\times 10^{21} }{6.022\times 10^{23} }[/tex]

Number of moles of the sample = 0.003721355 mole

Now, we will determine the Atomic mass of the sample

From the formula,

[tex]Atomic\ mass = \frac{Mass}{Number\ of\ moles}[/tex]

Therefore,

Atomic mass of the sample = [tex]\frac{0.4272}{0.003721355}[/tex]

Atomic mass of the sample = 114.8 amu

The element that has an atomic mass of 114.8 amu is Indium. The symbol of Indium is In.

Hence, the symbol of the element is In.

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Answer:

The right answer is "3 g".

Explanation:

Given:

Initial mass substance,

[tex]M_0=24 \ g[/tex]

By using the relation between half lives and amount of substances will be:

⇒ [tex]M=\frac{M_0}{2^n}[/tex]

        [tex]=\frac{24}{2^3}[/tex]

        [tex]=3 \ g[/tex]

Thus, the above is the correct answer.

Solution :

1 lb = 453.592 g

1 gallon = 3785 g

For every 5 gallon gasoline = 5 lb of C is found

                                              = 5 x 453.592 g of C atoms

                                              = 2267.96 g of C atoms

Assume the consumption of car = 15 miles per kg of gasoline

The amount of gasoline used per year  [tex]$=\frac{12000}{15}$[/tex]

                                                                   = 800 kg

In gallons = [tex]$\frac{800}{3.785} = 211.36\text{ gallons}$[/tex]    

5 gallons will produce = 2267.96 g of C atoms

Therefore,  

211.36 gallons will produce = [tex]$\frac{211.36 \times 2267.96}{5}$[/tex]

                                             = 95871.21 g

                                             = 95.87 kg

or                                           = 25.32 gallon

Answer:

The postabsorptive state (also called the fasting state) occurs when the food is already digested and absorbed, and it usually occurs overnight, when you sleep (if you skip meals for some days, you will enter in this state).

The catabolic state is the metabolic breakdown of molecules into simpler ones, releasing energy (heat) and utilizable resources.

Now, when you are in a postabsorptive state, the glucose levels start to drop, then the body starts to depend on the glycogen stores, which are catabolized into glucose, this is defined as the start of the postabsorptive state.

So yes, as the postabsorptive states, catabolic processes start to happen, so the statement is true.

Answer:

The correct answer is - 9935 years approximately.

Explanation:

Let z be the age in years to be found:

(15300 disintegrations) x (1.0 g / 0.250 g) / (1.84×10^4 disintegrations)

= 3.3260

half life of carbon = (1/2)^(z/5730 yr)

Solve for z

3.3260 = (1/2)^(z/5730)

Take the log of both sides:

log 3.3260  = (z/5730) log (1/2)

log 3.3260 / log (1/2) = z/5730

z = 5730 log 3.3260 / log (1/2)

= 1.73378816*5730

= 9935 years approximately.

Answer:

true

Explanation:

Answer:

See explanation

Explanation:

Sugar is a polar crystalline substance. The sugar crystal is capable of dissolving in water since it is polar.

When sugar dissolves in water, a sugar solution is formed. If I want to separate the sugar from the water in the solution, I have to boil the solution to a very high temperature.

When I do that, the water in the sugar solution is driven off and the pure sugar crystal is left behind.

Answer:

[tex]V_2= 736mL[/tex]

Explanation:

Hello there!

In this case, according to the given information, it turns out possible for us to solve this problem by using the combined gas law:

[tex]\frac{P_2V_2}{T_2}= \frac{P_1V_1}{T_1}[/tex]

Thus, we solve for the final volume by solving for V2 as follows:

[tex]V_2= \frac{P_1V_1T_2}{T_1P_2}[/tex]

Now, we plug in the variables to obtain the result in milliliters and making sure we have both temperatures in Kelvins:

[tex]V_2= \frac{1.20atm*735mL*279K}{(112+273)K*660/760atm}\\\\V_2= \frac{1.20atm*735mL*279K}{(112+273)K*660/760atm}=736mL[/tex]

Regards!

Answer:

c......................

Answer:

electrons will fill the lowest energy orbitals first and then move up to higher energy orbitals only after the lower energy orbitals are full

Answer:

Explanation:

The reaction between dimethyl malonate which is an active methylene group with an (∝, β-unsaturated carbonyl compound) i.e methyl vinyl ketone is known as a Micheal Addition reaction. The reaction mechanism starts with the base attack on the β-carbon to remove the acidic ∝-hydrogens and form a carbanion. The carbanion formed(enolate ion) attacks the methyl vinyl ketone(i.e. a nucleophilic attack at the β-carbon) to give a Micheal addition product, this is followed by the protonation to give the neutral product.

Answer:

[tex]Age=1040.55 million\ years[/tex]

Explanation:

From the question we are told that:

Initial Rock atoms [tex]a_1=2200atoms of 235^U[/tex]

Final Rock atom [tex]a_2=800 of  235^U[/tex]

Age of half life 713 million years

Generally the equation for Age is mathematically given by

[tex]\frac{1}{2^n}=\frac{800}{2200}[/tex]

[tex]\frac{1}{2^n}=\frac{1}{2.750}[/tex]

[tex]n=1.46[/tex]

Therefore

[tex]Age=713*1.46[/tex]

[tex]Age=1040.55 million\ years[/tex]

Answer:

I do not speak Spanish.

Explanation:

When electron goes from a higher shell to lower shell then it loses energy .

So, when an electron moved from shell n = 2 to shell n = 1 then a photon of energy is released.

Answer:

4.77mol is the correct answer

Molar mass of Acetone

Now

Moles of Acetone:-

Amount of heat:-

Answer:

1)  [tex]molality = 0.19[/tex]

2)  [tex]Mole\ fraction= 0.003486[/tex]

3)[tex]Mass\ percent = 2.8%[/tex]

Explanation:

Concentration of Tartaric acid=0.190mole /l

1)

Generally

[tex]Mass\ of\ tartaric\ acid = 150.087 *0.190[/tex]

[tex]Mass\ of\ tartaric\ acid = 28.5 g[/tex]

Since 1L of solution tartartic acid is

[tex]T_{1l}= density * volume[/tex]

[tex]T_{1l}= 1.016Kg / L X 1 L[/tex]

[tex]T_{1l}= 1016[/tex]

Therefore

[tex]Mass of solvent = 1016-28.5[/tex]

[tex]Mass of solvent = 987.5 g[/tex]

Generally the equation for molality is mathematically given by

[tex]molality = \frac{moles}{Kg}[/tex]

[tex]molality = \frac{0.190 * 1000}{987.5}[/tex]

[tex]molality = 0.19[/tex]

2.

Generally the equation for Moles of water  is mathematically given by

[tex]Moles\ of\ water = \frac{mass}{mol wt}[/tex]

[tex]Moles\ of\ water = \frac{987.5}{18 }[/tex]

[tex]Moles\ of\ water= 54.86[/tex]

Therefore

[tex]Mole\ fraction = \frac{Moles\ of\ solute}{total\ moles}[/tex]

[tex]Mole\ fraction= \frac{0.190}{54.5}[/tex]

[tex]Mole\ fraction= 0.003486[/tex]

3

Generally the equation for Mass Percent is mathematically given by

[tex]Mass\ percent = \frac{mass\ of\ tartaric\ acid}{total mass}[/tex]

[tex]Mass\ percent = \frac{28.5* 100}{1016}[/tex]

[tex]Mass\ percent = 2.8%[/tex]

Answer:

Al^3+

Explanation:

Solubility rules tell us what substances are soluble in water. Since NaCl was added and no precipitate was observed, the mercury II ion is absent.

Addition of Na2SO4 does not form a precipitate meaning that Ba^2+ is absent.

If a precipitate is formed when NaOH is added, the the ionic reaction is as follows;

Al^3+(aq) + 3 OH^-(aq) ------> Al(OH)3(s)

Answer:

hydrogen ions (H⁺) and chloride ions (Cl⁻)

Explanation:

Hydrochloric acid (HCl) is a strong acid. That means that the compound dissociates completely into ions when is dissolved in water, as follows:

HCl → H⁺ + Cl⁻

The equilibrium is completely shifted to the right side (products). Thus, it is considered that the concentration of the non-dissociated compound (HCl) is negligible, and the major specials present in the solution are the hydrogen ions (H⁺) and chloride ions (Cl⁻).

Explanation:

Chemical reactions can exhibit different rate constants at differing:

i)initial concentrations

ii)volumes of container

iii) temperatures

iv)none of the above.

The rate constant of a reaction is constant at a particular temperature.

It is not depending on the initial concentration of the reactants. It varies with temperature.

Thus, among the given options the correct answer is Temperatures.

Chemical reactions can exhibit different rate constant at different temperatures. Hence, the correct option is temperature.

The rate constant is the proportionality constant in the equation that expresses the relationship between the rate of a chemical reaction and the concentrations of the reacting substances.

Chemical reactions proceed at vastly different speeds depending on the nature of the reacting substances, the type of chemical transformation, the temperature, etc.

For a given reaction, the speed of the reaction will vary with the temperature, the pressure, and the amounts of reactants present.

The rate constant goes on increasing as the temperature goes up, but the rate of increase falls off quite rapidly at higher temperatures.

On the other hand, the volume of the container, initial concentration does not affect the rate constant.

Therefore, Chemical reactions can exhibit different rate constant at different temperatures. Hence, the correct option is temperature.

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Answer:

The correct solution is "3.28 m".

Explanation:

According to the question,

Mol fraction of solvent,

= 0.0558

Molar mass of water,

= 18 g/mol

Mol of H₂O in 1000 g water,

= 55.55 mol

Now,

Let the mol of solute will be "x mol".

Total mol in solution will be "55.55 + x".

As we know,

⇒ The mol fraction of solvent = [tex]\frac{x}{55.55+x}[/tex]

                                        [tex]0.0558=\frac{x}{55.55+x}[/tex]

                                                [tex]x=0.0558[55.55+x][/tex]

                                                [tex]x=3.09969+0.0558x[/tex]

                               [tex]x-0.0558x=3.09969[/tex]

                                               [tex]x=\frac{3.09969}{0.9442}[/tex]

                                                  [tex]=3.38 \ m[/tex]

Answer:

Se

Explanation:

First of all, we must note that any element that we must choose is an element that is in group sixteen.

Elements of groups 16 have six electrons in their outermost shell which can be used for bond formation thereby yielding a total of twelve electrons on the valence shell.

However, this is only possible for the heavier members of the group 16 (from sulphur downwards) which are able to expand their octet.

Oxygen can not expand its octet hence it is not the answer.