Since we know the original mass of this sample, we can calculate the concentration in ppm based on that value. Thanks for contributing an answer to Chemistry Stack Exchange! KEYWORDS (Audience): Second-Year Undergraduate; KEYWORDS (Domain): Analytical Chemistry ; KEYWORDS (Pedagogy): Hands-On Learning / Manipulatives; KEYWORDS (Subject): Fluorine; Cited By This article is cited by 21 publications. How can I label staffs with the parts' purpose, Two PhD programs simultaneously in different countries. �'b:ژ1s�q���+���>4�C�O��[U� endstream endobj startxref y = 59.8x +600.8$$ Sodium fluoride has a molecular weight of 42 MW Na (23) + F (19) = 42 NaF in toothpaste is 0.243% weight/volume of NaF (read the toothpaste tube) Convert % NaF to mg/g of NaF compound multiply by 10 = 0.243 x 10 = 2.43 mg NaF/g MAINTENANCE WARNING: Possible downtime early morning Dec 2/4/9 UTC (8:30PM…, “Question closed” notifications experiment results and graduation, Calculating Redox Potential; Coupled Reactions, Calculating the pH of a saturated calcium fluoride solution. i get the same answer. $0.7540~\mathrm{g}$ of toothpaste was diluted in a$50~\mathrm{mL}$ and tested to obtain a EMF value of $390$. Use MathJax to format equations. However, at this point you can multiply by the molar mass of fluoride, 18.998 g/mol, to get grams of fluoride, not moles, specifically, 0.0002835 g $\ce{NaF}$. Express the fluoride ion concentration in the toothpaste as %F. &�R ��]@,����gd0 ��� How to solve a linear problem A x = b in PETSC when matrix A has zero diagonal enteries? %%EOF Construct a polyhedron from the coordinates of its vertices and calculate the area of each face. 34 0 obj <> endobj what is the ppm of $\ce{F-}$ in $198~\mathrm{g}$ of toothpaste? @Spencer-Trinh I'd guess you're past caring at this point, but I'm curious, was this a word problem or a lab experiment? MathJax reference. The MQCbenchtop Nuclear Magnetic Resonance (NMR) analyser offers a simple, non-destructive and rapid method for the measurement of fluoride concentration in toothpastes. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. endstream endobj 39 0 obj <>stream $\frac{0.0002835 \textrm{ g } \ce{F-}}{0.7540 \textrm{ g toothpaste}}\times 1000000 = 376.0\textrm{ ppm }\ce{F-}$. Making statements based on opinion; back them up with references or personal experience. Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. Parts per million is a mass-based concentration measure. Would you mind writing your comment up and posting it as an answer? H�lSM��0��W�іB ��V�^�[���+ǎl�i�}�Ƥ�v/0��]U�Z�]U#���V���z����.��4���ڠ���p�3߉5;p�a^Z�ۤ��[�+�cw8 �ۿ����N� �xT�i���HP��4F��Ο��*���g}R�. Examples of back of envelope calculations leading to good intuition? The analyte concentration (μg/mL) in the original unknown solution (Cunk) can then be determined by dividing by the volume of the unknown fluoride solution (Vunk). Boil the solution gently for 2-3 minutes. First you need to take the equation for molarity: Analysis of Fluoride in Toothpaste The toothpaste sample should be prepared and analyzed at the same time the standards and your prepared unknown. The ppm unknown can be determined using the following equation: Ppm F- unk= ppm F -from graph x (100 mL/5mL) = ppm F-(graph) x 20. I multiplied by $18.998~\mathrm{g~mol^{-1}}$ to obtain $0.000283527~\mathrm{mol}$ of $\ce{F-}$. =�-�n ��|�R�,/3T�̢%�%i#G]��q&J6��%�1��d8�.2k�%dV��F�� kҋ5�͚! How come it's actually Black with the advantage here? By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. Regular OTC fluoride toothpastes are effective cavity preventers too. @JasonPatterson I think you already pretty much gave the answer. Transfer the toothpaste sample to a 250 mL beaker with a microspatula or stirring rod and add 50 mL 0.1 M KCl. � �9� The molecular weight of NaF is 41.99, and the density of the toothpaste is 0.9681g/cm 3. endstream endobj 38 0 obj <>stream Find the coordinates of a hand drawn curve. @I6I*�4R��b7"e*��h���*�Iq�A���'v�j�2���]&hz�WWl\W�f3I���!��DE�:1���Ӵ���6s6��L����N�e Determine the ppm F-in your unknown and in the toothpaste from the calibration curve. A linear regression line was obtained; $$\log(\ce{[NaF]})~(\mathrm{mol~L^{-1}})~ \mathrm{vs~EMF}: As … Multiplying by the molar mass gives you 0.0002835. thanks for your support, i guess it has to deal with the regression line, it must be wrong? hޤVmo�8�+��b��b�/�P m�.����: �7�R�����#%+qr����E��DJ�CEq�. Has the European Union taken any concrete steps towards reducing its economic dependency on China? 0 I'm stuck here, how can I calculate the ppm? I follow your method through moles of fluoride, but at that point, your units get messed up. Accurately weigh about 0.2 g of toothpaste into a 100 mL beaker. endstream endobj 35 0 obj <> endobj 36 0 obj <> endobj 37 0 obj <>stream To learn more, see our tips on writing great answers. Asking for help, clarification, or responding to other answers. How many pawns make up for a missing queen in the endgame? 49 0 obj <>/Filter/FlateDecode/ID[<1F6A54D718C2F8DE468B1D676AB45DF7><81D22B0591931F4CB526DBD73E3CFDA0>]/Index[34 28]/Info 33 0 R/Length 76/Prev 143969/Root 35 0 R/Size 62/Type/XRef/W[1 2 1]>>stream A toothpaste sample is prepared as follows: weigh the beaker plus the sample of toothpaste to determine the net weight of the toothpaste sample. It will be the same concentration as in the larger sample. The expected value of fluoride in toothpaste is $1000~\mathrm{ppm}$. It's similar in concept to percent mass, but instead of … 4Ҹ��߂�����˺%|ݒ��῝A ��n?�[æ��^���������/w^9J��Z��j'x�? It's similar in concept to percent mass, but instead of parts per hundred, it uses parts per million. ���(܃`ٰ�f��?r�f��>D���[�a�ԕ�$�&�~�����p�FکRDl\�����}}]��*J`�s�\�Վ�MQ�.f�F�����z�W�V��o4�T��iv?���4�,_�C�l��=�hBfb�X�u������WH��Ȕ�m�������M�:o5ټ��m��WE�fOE5��b�Mkn^�y� a�N毼�qĲφb�5?� jN�2/�\*A@GMO�I4�FU���V�4��߽�K���98�! I get the following: How do I legally resign in Germany when no one is at the office? I then multiplied by the factor: $\frac{198}{0.750}$ to obtain $0.074454015~\mathrm{g}$ of $\ce{F-}$ in the $198~\mathrm{g}$ of toothpaste. [��&��E!���P)t.�|�?�s%��`�C� �Ǘ��_4Q�&��ٮ���� �6`η{>�9��d�;�����[~h�PWQ�Ӓf��Qq?jd[���pl��v��ytP�n���I�v������3��XF}�"Z�8�t?sr0���q��,Oz塡$t���X�y���p�u�L���(�A�)#��]�i�M�v( ��/1�� site design / logo © 2020 Stack Exchange Inc; user contributions licensed under cc by-sa. A review of dental literature performed by Walsh concluded that a dentifrice must deliver a fluoride concentration of at least 1000 ppm to produce significant anticavity effects. h�b```f``2d`a`��� �� @ �X�$��'���\�L��g�^`�`��``h�� ��109�Ҽ@�6����9�ё*��_\�>(t>��a��u� Due to stoichiometry, this also equals $1~\mathrm{mol}$ of $\ce{F-}$. }c)!�b�ZY ��N����I�Z�^gC^$��kR;/�c����I��[��H��:)~#7�G?oO'����y���Λ�şrDsDF�qdp]���$J��� �3���ϣKxB)�M�?��8}N���:�A� n�P�-o�ca�V� ]�' �;tџd����=M�G@��R�f2« �����G�L;P�0�q\"��DG��v��t8���kh���p8~p�g�n��!x��k�{R}���kV�A�]LV�lav��Q���4���~֗�������7�0��&��|˼=9&��6�i{��+Pв�չ�*L����^*��s*B�y�������Z��n�����6���8��M��� ���G���RN�TCP��=3��\i��m`lp�s�j��T�l~Zk�ny!2�F��ms�5E ��_��}�� I plugged in $390$ into the eqn to get $-3.525$, taking the antilog to obtain $0.0002985$, and times it by the volume $0.05~\mathrm{L}$ to get the moles of $\ce{NaF}$. 1. If a person is dressed up as non-human, and is killed by someone who sincerely believes the victim was not human, who is responsible? 61 0 obj <>stream Working with your numbers gives me the same result through moles of $\ce{NaF}$. rev 2020.11.24.38066, The best answers are voted up and rise to the top, Chemistry Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us, I'm having difficulty getting your expected answer. h�bbd``b`Z $�� �rH0��$*A�pn.�x ⶁX� B��H�e`$��ϸ�@� n� %PDF-1.5 %���� However, at this point you can multiply by the molar mass of fluoride, 18.998 g/mol, to get grams of fluoride, not moles, specifically, 0.0002835 g N a F. Parts per million is a mass-based concentration measure. The molarity of NaF (sodium fluoride) in a brand of toothpaste was found to be 3.16*10 -4 M. How do I determine the %w/v (percent weight by volume) of fluoride ion in the toothpaste from the molarity? *�H��>M�����MN5�������6�n�s}l;�v���UO*EV��&��o��>���ծ NMR detects the soluble fluoride content in toothpastes, which is the most important parameter in … Considers the theory behind the operation of the ion-selective electrode and its application to determine the fluoride in toothpaste. My strands of LED Christmas lights are not polarized, and I don't understand how that works. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy.
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