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mylen [45]
3 years ago
6

If you were helping a friend do stoichiometry problems, what would you tell them about how they might use subscripts and coeffic

ients in their problem solving? Use Sentence(s).
Chemistry
2 answers:
Jet001 [13]3 years ago
8 0
Im not sure if this will help but... your subscripts in a balanced equation are used to calculate the molar mass of the compound. And your coefficients are used to get the ratios. so for example we have this balanced equation
Be3N2 + 6H2O= 3Be(OH)2 + 2NH3  and you have to find the molar mass of 6h2o, you need to multiply the subscript by the atomic mass and then add them together to get the overall molar mass.  * 2(1.01) + 16.00= 18.02 g/mol
and if a question wants to know the limiting or excess regent you would use the coefficients to find out the ratio between the compounds.
 
____ [38]3 years ago
6 0

<u>Answer:</u> By using law of conservation of mass.

<u>Explanation:</u>

A balanced chemical equation always follow law of conservation of mass.

This law states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form. This also means that total number of individual atoms on reactant side must be equal to the total number of individual atoms on the product side.

The chemical reaction for the formation of water follows the equation:

2H_2+O_2\rightarrow 2H_2O

Total mass on reactant side:  [2(2\times 1)+(2\times 16)]=36g/mol

Total mass on product side:  [2((2\times 1)+16)]=36g/mol

Hence, by using law of conservation of mass.

You might be interested in
How many atoms are in a sample of 175 grams of sodium (na)? 1.42 × 10^27 atoms 4.58 × 10^24 atoms 6.68 × 10^-21 atoms 1.26 × 10^
Alenkasestr [34]
Atomic mass Na = 22.99 u.m.a

22.99 g ------------------ 6.02x10²³ atoms
175 g -------------------- ?? atoms

175 x (6.02x10²³) / 22.99 => 4.58x10²⁴ atoms

hope this helps!
5 0
4 years ago
The atomic mass of the elements M,X and Q are 6,11 and 17 respectively. Use the valency electrons to explain how the atoms M and
Mamont248 [21]

Answer:

M is Li, X is boron, and Q is oxygen.  MX is LiB, lithium bromide.  QX is BO, boron oxide (not Body Odor).

Explanation:  The atomic masses don't match exactly with those listed in the periodic table.  Boron, Oxygen, and Lithium come the closest.

Lithium reacts with bromine since it happily donates it's single 2s electron to bromine's 4p orbital to fill bromine's 4s and 4p valence orbitals to go from 7 to 8 valence electrons, it's happy state.

Boron reacts with oxygen to form B2O3, which I'll happily write as O=BOB=O, since my name is Bob.  This is more complex, but both elements want to move electrons around in order to reach a more stable electron configuration.  Boron has 3 valence electrons and oxygen has 6.  So each oxygen needs 2 electrons to fill it's outer shell and boron is happy to lose it's 3 valence electrons to reach an outer shell equiovalent to helium.  So 2 borons contribute a total of 6 electrons, and the 3 oxygens have room for a total of 6 electrons to fill their outer shell.

8 0
3 years ago
How can a change to another population could affect births and deaths in the parrot population.
forsale [732]

Answer:

read it first

Explanation:

Population change is governed by the balance between birth rates and death rates. If the birth rate stays the same and the death rate decreases, then population numbers will grow. If the birth rate increases and the death rate stays the same, then population will also grow.

hope it helps

6 0
2 years ago
An organic compound absorbs strongly in the IR at 1687 cm1. Its 'H NMR spectrum consists of two signals, a singlet at 2.1 ppm an
tatuchka [14]

This question does not contain the structures of the molecules. The structures in Daylight SMILES format are:

I. C1=CC=CC=C1C(=O)C

II. C1=CC=CC=C1CC=O

III. C1=CC(C)=CC=C1C=O

IV. C1=CC=CC=C1CCC

V. C1=CC=CC=C1C(C)C

The structures are also attached

Answer:

The structure of compound IV is consistent with the information obtained analysis

Proposed structures for the ions with m/z values of 120, 105,77 and 43 are (also attached):

C1=CC=CC=C1C(=[OH0+])C |^1:7|

C1C([CH0+]=O)=CC=CC=1

C1[CH0+]=CC=CC=1

C(#[OH0+])C

respectively

Explanation:

The IR peak at 1687 cm⁻¹ is indicative of an α unsaturated carbonyl carbon. While the 1H NMR singlet is of the methyl group next to carbonyl and the multiplet near 7.1 ppm is a characteristic peak of benzene. This data shows points towards structure I.

Mass spectrum peak at 120 m/z is of molecular ion peak. In the case of carbonyl-containing molecule, this peak is observable. The signal at 105 shows the loss of a methyl group next to the carbonyl. m/z value of 77 is the characteristic cationic peak of benzene, while the peak at 43 infers the formation of acylium ion (RCO+) due to α-cleavage. All this data agrees with the structure of acetophenone (Structure 1)

6 0
4 years ago
What is the entropy of this collection of training examples with respect to the positive class B. What are the information gains
Alenkinab [10]

The data set is missing in the question. The data set is given in the attachment.

Solution :

a). In the table, there are four positive examples and give number of negative examples.

Therefore,

$P(+) = \frac{4}{9}$   and

$P(-) = \frac{5}{9}$

The entropy of the training examples is given by :

$ -\frac{4}{9}\log_2\left(\frac{4}{9}\right)-\frac{5}{9}\log_2\left(\frac{5}{9}\right)$

= 0.9911

b). For the attribute all the associating increments and the probability are :

  $a_1$   +   -

  T   3    1

  F    1    4

Th entropy for   $a_1$  is given by :

$\frac{4}{9}[ -\frac{3}{4}\log\left(\frac{3}{4}\right)-\frac{1}{4}\log\left(\frac{1}{4}\right)]+\frac{5}{9}[ -\frac{1}{5}\log\left(\frac{1}{5}\right)-\frac{4}{5}\log\left(\frac{4}{5}\right)]$

= 0.7616

Therefore, the information gain for $a_1$  is

  0.9911 - 0.7616 = 0.2294

Similarly for the attribute $a_2$  the associating counts and the probabilities are :

  $a_2$  +   -

  T   2    3

  F   2    2

Th entropy for   $a_2$ is given by :

$\frac{5}{9}[ -\frac{2}{5}\log\left(\frac{2}{5}\right)-\frac{3}{5}\log\left(\frac{3}{5}\right)]+\frac{4}{9}[ -\frac{2}{4}\log\left(\frac{2}{4}\right)-\frac{2}{4}\log\left(\frac{2}{4}\right)]$

= 0.9839

Therefore, the information gain for $a_2$ is

  0.9911 - 0.9839 = 0.0072

$a_3$     Class label      split point       entropy        Info gain

1.0         +                        2.0            0.8484        0.1427

3.0        -                         3.5            0.9885        0.0026

4.0        +                        4.5            0.9183         0.0728

5.0        -

5.0        -                        5.5            0.9839        0.0072

6.0        +                       6.5             0.9728       0.0183

7.0        +

7.0        -                        7.5             0.8889       0.1022

The best split for $a_3$  observed at split point which is equal to 2.

c). From the table mention in part (b) of the information gain, we can say that $a_1$ produces the best split.

4 0
3 years ago
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