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3 years ago

How to round significant figures

Chemistry

2 answers:

DerKrebs [107]3 years ago

8 0

Answer:look at the first non-zero digit if rounding to one significant figure.

look at the digit after the first non-zero digit if rounding to two significant figures.

draw a vertical line after the place value digit that is required.

look at the next digit.

Explanation: Google ;DDDD

marissa [1.9K]3 years ago

7 0

Explanation:

To round to a significant figure:

look at the first non-zero digit if rounding to one significant figure
look at the digit after the first non-zero digit if rounding to two significant figures
draw a vertical line after the place value digit that is required
look at the next digit
if it's 5 or more, increase the previous digit by one
if it's 4 or less, keep the previous digit the same
fill any spaces to the right of the line with zeros, stopping at the decimal point if there is one

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A scientist wants to make a solution of tribasic sodium phosphate, Na3PO4, for a laboratory experiment. How many grams of Na3PO4

Anna71 [15]

Answer:

31.652g of Na3PO4

Explanation:

We'll begin by calculating the molarity of Na3PO4 solution. This can be achieved as shown below:

Na3PO4 will dessicate in solution as follow:

Na3PO4(aq) —> 3Na+(aq) + PO4³¯(aq)

From the balanced equation above,

1 mole of Na3PO4 produce 3 moles of sodium ion, Na+.

Therefore, xM Na3PO4 will produce 1.10M sodium ion, Na+ i.e

xM Na3PO4 = (1.10 x 1)/3

xM Na3PO4 = 0.367M

Therefore, the molarity of Na3PO4 is 0.367M.

Next, we shall determine the number of mole of Na3PO4 in the solution. This is illustrated below:

Molarity of Na3PO4 = 0.367M

Volume = 525mL = 525/1000 = 0.525L

Mole of Na3PO4 =..?

Molarity = mole /Volume

0.367 = mole /0.525

Cross multiply

Mole of Na3PO4 = 0.367 x 0.525

Mole of Na3PO4 = 0.193 mole.

Finally, we shall convert 0.193 mole of Na3PO4 to grams. This is illustrated below:

Molar mass of Na3PO4 = (23x3) + 31 + (16x4) = 164g/mol

Mole of Na3PO4 = 0.193 mole

Mass of Na3PO4 =.?

Mass = mole x molar mass

Mass of Na3PO4 = 0.193 x 164

Mass of Na3PO4 = 31.652g

Therefore, 31.652g of Na3PO4 is needed to prepare the solution.

6 0

3 years ago

Please help me I need these answers

Cerrena [4.2K]

1 is true

2 is d 7

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3 years ago

Can someone help me with these questions?

Gennadij [26K]

Answer:

9) Substitution Reaction

10) Covalent Bond

11) Ionic Bond

12) Covalent Bond

13) Ionic Bond

14) 9 atoms

Explanation:

9) Substitution Reaction: Substitution reaction is a chemical reaction in which one atom, ion or species replaced by another atom, ion or species

10) Covalent Bond: Covalent bond is a bond that formed between two nonmetals, when both the species are non metal, the electronegativity of both the nonmetals are comparatively same, hence any of both do not pulls completely electron of other & the bond is formed by the sharing of electron.

11) Ionic Bond: We know that nonmetals have high electronegativity than those of metals, due to high electronegativity non metals pulls the electrons of metals but there is enough interaction that non metal do not escape after pulling the electron, & an ionic bond generates where non metals possess negative charge & positive charge goes to metal.

12) Covalent Bond: The bond formed between two atoms having less electronegativity diffrence by sharing of electron pair is know as covalent bond. for e.g the Carbon - Hydrogen bond in methane (CH4) molecule is covalent bonded because the electronegativity of carbon is 2.5 & that of hydrogen is 2.1 which is almost close, hence the bond formed is covalent.

13) Ionic Bond: The bond formed between two atoms having high electronegativity diffrence & the bond formed is due to complete transfer of electron by one species. For e.g. NaCl the sodium is a metal having electronegativity 0.9 and chlorine is non metal having electronegativity 3.0 the electronegativity diffrence is too high, hence the chlorine behaves as Cl- ion that of sodium as Na+, both the components behaves as ion but they are bonded &that bond is called as Ionic bond.

14) 9 Atoms: One molecule of water (H2O) posses three atoms, two hydrogen atoms & one oxygen atom, the number of atoms in 3 molecules of water 3×3 = 9 atoms.

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2 years ago

Which aldehyde is an intermediate in the reduction of ethyl benzoate with lithium aluminum hydride?

garri49 [273]

Answer:

tetrahedral aldehyde

Explanation:

The reaction begins with a hydride nucleophile reacting with the ester carbonyl carbon to form the tetrahedral intermediate.

The carbonyl reforms to produce an aldehyde with the loss of the alkoxide ion.
The resulting aldehyde undergoes a subsequent reaction with a hydride nucleophile to form another tetrahedral intermediate. The carbonyl is not able to reform, because there are no stable leaving groups.
Therefore, the tetrahedral intermediate is protonated to produce a primary alcohol.

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3 years ago

Please help me with this chem question, I’ll mark you brainiest if it’s right. There’s multiple answers for this one.

Kazeer [188]

Answer:

Option A. KCl (aq)

Option D. Mg(OH)₂(s

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

MgCl₂(aq) + KOH(aq) —>

In solution, MgCl₂(aq) and KOH(aq) will dissociate as follow:

MgCl₂(aq) —> Mg²⁺(aq) + 2Cl¯(aq)

KOH(aq) —> K⁺(aq) + OH¯(aq)

MgCl₂(aq) + KOH(aq) —>

Mg²⁺(aq) + 2Cl¯(aq) + 2K⁺(aq) + OH¯(aq) —> 2K⁺(aq) + 2Cl¯(aq) + Mg(OH)₂ (s)

MgCl₂(aq) + KOH(aq) —> 2KCl (aq) + Mg(OH)₂(s)

Thus, the products of the above reaction are: KCl(aq) and Mg(OH)₂(s)

Thus, option A and D gives the correct answer to the question.

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3 years ago