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A 215-g sample of iron is heated by a chemist from 25.0°C to 90.0°C and 6.3 kJ of heat are absorbed by the iron (q).

Also known as specific heat, this is the quantity of energy required to increase a substance's temperature by 1 degree Celsius in one gram. The units of specific heat are typically calorie or joules a gram per degree Celsius. As an illustration, the specific heat of water is 1 calorie (4.186 joules) each gram per degrees C.

q = m × C × ΔT

q = m × C × (T[tex]_f[/tex] - T[tex]_i[/tex]),

q is the quantity of heat energy a substance gains or loses (J)

m = mass of sample (g)

C = specific heat capacity (J °C-1 g-1)

T[tex]_f[/tex] = final temperature (°C)

T[tex]_i[/tex] = initial temperature (°C)

Thus:

q = (215 g) × (0.45 J oC-1 g-1) × (90 - 25)°C

q = 6288.75 J

q = 6288.75 J = 6.3 kJ

The iron absorb 6.3 kJ of heat (q).

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Answer:

metallic compounds are good conductors of electricity.

metallic compounds have high boiling points

Ask a question the first things that scientists do when starting a new investigation.

Scientific practices, which include things like answering questions, creating and using models, and having arguments, are cognitive, discursive, and social activities carried out in science classrooms with the goal of developing epistemic understanding and appreciation of the nature of science.

Participating in these activities not only makes students' knowledge more meaningful and deeply ingrained in their worldview, but it also aids them in developing an understanding of the disciplinary and transdisciplinary ideas of science and engineering.

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Yes, to determine the molar mass of an unknown solute from the freezing point depression the freezing points of both the pure solvent and the solution need to be measured.

The depression of the freezing point is a and it is given by the following formula,

ΔT f = T°f - T f

Here T°f is the freezing point of pure solvent

T f is the freezing point of the solution made by adding non-volatile solute to solvent

The freezing point depression is directly proportional to the molality of the solution

T(f) ∝ m

T(f)= K f x m

Here K f is the proportionality constant.

Hence, to determine the molar mass of an unknown solute from the freezing point depression the freezing points of both the pure solvent and the solution need to be measured.

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Answer:the electrons can possess only certain discrete energy values; values between those quantized values are not permitted.

Explanation:Both involve a relatively heavy nucleus with electrons moving around it, although strictly speaking, the Bohr model works only for one-electron atoms or ions.

The melting and boiling and density is given below :

Substance          melting point / °C         boiling point / °C       density / g cm⁻³

  E                           -259                                 -253                          0.09

 F                           1085                                 2580                         8.93

  G                                 -7                                     59                            3.1

 H                              -39                                   357                           13.6

  I                                -218                                  - 183                       0.0013

A) substances are gases at room temperature:

    E and I are gases at room temperature because the melting and boiling point are below at room temperature.

B) substances are liquids at room temperature:

    G and H  are liquids at room temperature because substances are liquid at room temperature if melting point is below room temperature and boiling point is above room temperature.

C) substances are solid at room temperature :

   F is solid at room temperature because its melting point is above room temperature.

D) substances are most likely to be metal :

   F is metal because metals have very high melting and boiling point except mercury.

E) substance are most likely to be mercury :

    H is most likely to be mercury because mercury has boiling point -38°C and melting point is 356°C and density is 13.5 g/ cm³ and mercury is metal with exception.

G) substances will be liquid at -210°C :

  I is liquid at -210°C because substance is liquid when its melting point is below temperature and boiling point is above temperature.

H) substances are most likely to be bromine :

  G is more likely to be bromine because melting and boiling point and density of G is close to bromine.

I)  substances which are least dense non metal :

   E is least dense non metal because its melting and boiling point and density is close to least dense non - metal.

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Answer:

okay

Explanation:

The fire triangle's three sides illustrate the three elements of fire: heat, fuel and oxidization. The three elements must be combined in the right proportions for a fire to occur. If any of the three elements are removed, the fire is extinguished

From the table shown in the question;

Volume of aluminum bar = 15.52 cm^3

Volume of the rod =  23.8 cm^3

The volume of the iron bolt can only be obtained by the displacement method.

The term volume refers to the space that is occupied by an object. We know that the volume of an object could be obtained in different ways depending on the nature of the object. If the object is a solid, we could look at the dimensions of the solid or we could use the dimensions of the solid. The actual method that we finally use is peculiar to the object whose volume we intend to measure.

In order to obtain the volume of the aluminum bar;

Volume = length * width * height

Volume = 9.7 * 1.6 * 1.0 = 15.52 cm^3

In order to obtain the volume of the rod;

Volume = Area * length

Volume = 3.14 * (1.7)^2/4 * 10.5

Volume = 23.8 cm^3

We can not obtain the volume of the iron bolt by this method because it is an irregular solid hence we have to use the displacement method.

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Answer:

Because it is the same element but has different atomic mass

The molality of the glycerol solution is 3.854mol/kg

The number of moles of solute present in a solution equal to 1 kg or 1000 g of solvent is referred to as its molality.

Given:

Mass, m1 of glycerol = 15.01g

Mass, m2 of ethanol = 42.3g

Molar mass, mm1 of glycerol = 92.095g/mol

Molar mass, mm2 of ethanol = 46.069g/mol

To find:

Molality, m = ?

Formula:

Molality, m = moles of solute / kg of solvent

Calculations:

No. of moles of glycerol = 15.01 x (1/92.095)

n = 0.163 mols

Molality, m = 0.163 / 0.0423g

Molality, m = 3.854mol/kg

Result:

3.854mol/kg is the molality of the glycerol solution.

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The pH of a monoprotic weak acid which is 80 percent ionised with a strentght of 0.05m is 1.39

What is pH ?

A scale called pH , which traditionally stood for "potential of hydrogen" (or "power of hydrogen"), is used in chemistry to describe how acidic or basic an aqueous solution is. Lower pH values are recorded for acidic solutions (solutions with higher H+ ion concentrations) than for basic or alkaline solutions. The concentration of hydrogen ions in the solution is shown inversely by the pH scale, which is logarithmic.

pH + pOH = 14

[H + ]=0.05×0.80=0.04M

Now, Here, pH=−log[H + ]=−log0.04=1.39

The pH of a monoprotic weak acid which is 80 percent ionised with a strentght of 0.05m is 1.39

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The empirical formula of the compound is C₃H₆O

The empirical formula is determined as follows from the equation of the reaction as follows:

mass of CO₂ produced = 15.17 mg = 0.01517 g

moles of C in the sample = 0.01517/44  = 0.000344 moles

mass of C in the sample =  0.0000344  * 12 = 0.00413 g

mass of H₂O produced  = 6.19 mg = 0.00619 g

moles of H in the sample = 0.00619/18 * 2 = 0.000688 moles

mass of H in sample = 0.000688 g

mass of oxygen in the sample = 0.00667 g - (0.00413 g + 0.000688 g)

mass of oxygen in the sample = 0.00185

moles of oxygen = 0.00185/16 = 0.000116

Ratio of C : H : O = 0.000344 : 0.000688 : 0.000116

Ratio of C : H : O = 3 : 6 : 1

Empirical formula of compound = C₃H₆O

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Answer: S

:) hope this helps you!

Answer: F=m*a

Explanation: Force equals mass times acceleration!

I hope this helps!

Answer:

This is an example of a random error because the timer is adding an extra second onto each runner's time, which is not an accurate representation of their true time. This error is not systematic, meaning that it does not affect all runners in the same way or add the same amount of time onto their times.

Explanation:

Give me brainliest if that helped :)

Answer:

0.005 moles

Explanation:

120cm^3 = 0.12dm^3

1mol is always 24dm^3 of gas at rtp

0.12 ÷ 24 = 0.005 moles

A high amount of naturally occurring NaCl is considered evidence of a compound with a low activation energy and is denoted as option A.

This is referred to as the minimum amount of energy which is needed for a chemical reaction to occur and is dependent on various factors.

A compound which has a low activation energy will have a high yield sue to the ease in which the reactants are being converted into products. in this scenario, the high amount of naturally occurring NaCl signifies a low activation energy which is why option A was chosen as the correct choice.

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[tex]=3h\ x\ \frac{60 \min}{1h }\ x\ \frac{60\ sec}{1\ min}[/tex]

[tex]=10800\ sec[/tex]

Set up your equation so that your units cancel until you get to the unit you want. Hours and hours would cancel, and min and min would cancel, leaving you with sec which is the unit you want.

Remember: they can only cancel if one is on top and the other is on the bottom.

Answer:

1hr=60minutes

1min=60 seconds

then we have to convert 3hrs into seconds

now,

3*60*60=10,800

The scientific method is an experimentation technique used to investigate data and answer questions. All sciences, including chemistry, physics, geology, and psychology, follow the scientific method. These scientists ask various questions and conduct different tests. They do, however, apply the same fundamental technique to arrive at logical and evidence-based conclusions. Scientists change the scientific method when direct experimentation is not possible. Understanding the phases of the scientific process can assist you in focusing your scientific inquiry and working through your observations and data to get the best possible response.

The scientific method consists of seven phases.

1. Pose a query. The scientific approach begins with posing a question that you want answered.

2. Conduct research.

3. Create your theory.

4. Experiment to put your hypothesis to the test.

5. Make a note of it.

6. Analyze the findings and reach a conclusion.

7. Display your results.

Answer:

A black spot will remain on the silver coin, but not on the nonsilver coin. Mustard naturally contains sulfur compounds, and sul- fur reacts with silver to form a black precipi- tate of silver sulfide (Ag2S)

Explanation:

The ph of a buffer solution was obtained by dissolving 17.0 g of [tex]KH_{2} PO_{4}[/tex]  and 30.0 g of  [tex]Na_{2} HPO_{4}[/tex]   in water and then diluting to 1.00L is 7.43.

We will apply the Henderson-Hasselblach equation to determine the pH:

pH= pKa + Log [A/AH]

when [tex]Na_{2} HPO_{4}[/tex] molar mass is 142 g/mol

A is the conjugate base [tex]HPO_{4} ^{-}[/tex] ions and as a result,

[tex][A]= \frac{30g}{142 g/mol}[/tex]

= 0.211 M

[tex]KH_{2} PO_{4}[/tex] has a molar mass of 136 g/mol.

Given that AH is the weak acid [tex]H_{2} PO_{4} ^{-}[/tex] ion,

[AH] = [tex]\frac{17.0 g}{136 g/mol.}[/tex]

= 0.125 M

and with [tex]H_{3} PO_{4}[/tex] having a pKa value of 7.21

then, substituting

∴ pH = 7.21 + log (0.211 / 0.125)

= 7.21 +0.227

=7.43

The pH of a buffer solution is 7.43.

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The student that had the most accurate and precise data is Mel (option D).

Accuracy is the degree of conformity of a measure to a true or standard value i.e. closeness to a standard or true value.

On the other hand, precision is the ability of a measurement to be reproduced consistently i.e. the closeness of measured values.

According to this question, students calculated the mass in grams of the baking soda being used.

It can be said that Mel, which measured the following values: 0.44g, 0.46g, 0.45g had the most accurate and precise value because they are both close to themselves and the true value.

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Answer:

D

Explanation:

Mel

When performing an extraction between an aqueous solution and an organic solution or organic compound, density will determine the layer ending up at the bottom of the separation funnel.

In chemistry, a separatory funnel is a kind of funnel that separates two immiscible liquids.

It is a transparent funnel and when two immiscible liquids i.e aqueous and organic solution is poured into it, and then allowed to stand, after a while a distinguished layer is formed setting them apart from each other.

Due to the difference in density, the extraction becomes easier as the aqueous layer has a low density and stays at the top while the organic layer is at the bottom.

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6.508 g mass of of NH3 is formed when 5.36 g of nitrogen gas reacts with excess hydrogen gas.

                                N2 + 3 H2  → 2 NH3

The molar mass of N2 is 28.0 g/mol. The molar mass of NH3 is 17 g/mol.

To find the mass of NH3:

=5.36 x 2 x (17 / 28)

=182.2 / 28

= 6.508 g

The mass of ammonia is 5.36 g.

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Answer:

Around 31536000 seconds (depending on which days you want to exclude)

Explanation:

60 seconds in 1 minute

60 minutes in an hour

24 hours in 1 day

365 days in 1 year

60 * 60 * 24 * 365

Answer:

I believe that would be a liquid.

Explanation:

The ratio of the concentration of formate to formic acid required in a buffer system is 3.16 : 1.

pH = 4.25; pH of the solution

pKa = 3.75

Henderson–Hasselbalch equation: pH = pKa + log(cs/ck)

4.25 = 3.75 + log(cs/ck)

log(cs/ck) = 4.25 - 3.75

log(cs/ck) = 0.5

cs/ck = 10∧(0.5)

cs/ck = 3.16; ratio of formate to formic acid

A buffer can be defined as a substance that prevents the pH of a solution from changing by either releasing or absorbing H⁺ in a solution.

Buffer is a solution that can resist pH change upon the addition of an acidic or basic components and it is able to neutralize small amounts of added acid or base, pH of the solution is relatively stable.

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Answer:

B) 27.94

Explanation:

All other last digits are wrong except b

Answer:

[tex] \frac{39.25 + 150.}{6.773} = 27.94182[/tex]

Explanation:

[tex]1. \: (39.25 + 150.) \div (6.60 + 0.173) \\ 2. \: (39.25 + 150.) \div 6.773 \\ 3. \: (39.25 + 150.) \times \frac{1}{6.773} \\ 4. \: \frac{(39.25 + 150.) \times 1}{6.773} \\ 5. \: \frac{39.25 + 150.}{6.773} = 27.94182[/tex]